Related Experiment Video
Updated: Sep 15, 2025
Laser Capture Microdissection of Mouse Embryonic Cartilage and Bone for Gene Expression Analysis
Published on: December 18, 2019
RORβ Deficiency Inhibits Endochondral Ossification in Mice by Mediating the HIF-1α/VEGFA Signaling Pathway
Yifan Zhang1,2, Xingfu Bao1, Jun Ma3
1Department of Orthodontics, Hospital of Stomatology, Jilin University, Changchun, China.
Abstract:
Retinoic acid receptor-related orphan receptor beta (RORβ) is a ligand-dependent transcription factor essential for bone metabolism. While RORβ negatively regulates osteoblast differentiation and contributes to age-related or postmenopausal osteoporosis, its role in early skeletal development remains unclear. This study developed a Rorβ gene knockout (KO) mouse model using CRISPR/Cas9 to investigate its effects on endochondral ossification. At 4 weeks, Rorβ KO mice exhibited dwarfism and early-onset osteoporosis, with reduced femur length (-8.84%), lower cortical and trabecular bone mass, and impaired bone quality. The trabecular bone was fragile, with reduced surface osteoblasts and impaired osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs). Chondrogenesis was also disrupted, evidenced by a thinner growth plate, fewer chondrocytes, and a disorganized hypertrophic zone (HZ). The expressions of proliferation (Ki67) and hypertrophic differentiation (Collagen X) markers were significantly reduced. Mechanistically, RORβ deficiency downregulated hypoxia-inducible factor 1-alpha (HIF-1α) and its downstream target vascular endothelial growth factor A (VEGFA) in both the pre-hypertrophic zone (PHZ) of the growth plate and BMSCs. These findings identify RORβ as a critical regulator of endochondral ossification, linking its loss to skeletal defects via impaired HIF-1α/VEGFA signaling. This study provides insights into potential therapeutic strategies for skeletal diseases such as skeletal dysplasia.
Insights
Retinoic acid receptor-related orphan receptor beta (RORβ) is crucial for skeletal development. Loss of RORβ in mice caused dwarfism and osteoporosis by disrupting endochondral ossification via impaired HIF-1α/VEGFA signaling.
Area of Science:
- Endocrinology
- Developmental Biology
- Orthopedics
Background:
- Retinoic acid receptor-related orphan receptor beta (RORβ) is a transcription factor involved in bone metabolism.
- RORβ's role in early skeletal development and endochondral ossification is not well understood.
- Osteoporosis is a significant health concern, particularly in aging populations.
Purpose of the Study:
- To investigate the role of RORβ in endochondral ossification and early skeletal development.
- To characterize the skeletal phenotypes of RORβ-deficient mice.
- To elucidate the molecular mechanisms underlying RORβ's function in bone formation.
Main Methods:
- Generation of a Rorβ gene knockout (KO) mouse model using CRISPR/Cas9.
- Phenotypic analysis of Rorβ KO mice at 4 weeks of age, including bone mineral density, bone length, and microarchitecture.
- Histological examination of growth plates and analysis of chondrocyte differentiation.
- Assessment of osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs).
- Molecular analysis of key signaling pathways, including HIF-1α and VEGFA.
Main Results:
- Rorβ KO mice displayed dwarfism, reduced femur length, and decreased bone mass and quality.
- Trabecular bone was fragile with fewer osteoblasts and impaired BMSC osteogenic differentiation.
- Endochondral ossification was disrupted, characterized by a thinner growth plate and disorganized hypertrophic zone.
- Expression of proliferation and hypertrophic differentiation markers (Ki67, Collagen X) was significantly reduced.
- RORβ deficiency led to downregulation of HIF-1α and VEGFA in growth plate and BMSCs.
Conclusions:
- RORβ is essential for normal endochondral ossification and skeletal development.
- Loss of RORβ results in skeletal defects through impaired HIF-1α/VEGFA signaling.
- RORβ deficiency contributes to early-onset osteoporosis and may be implicated in skeletal dysplasias.
Related Concept Videos
01:24Bone Formation by Endochondral Ossification
01:24Regulation of Angiogenesis and Blood Supply
01:16TGF - β Signaling Pathway
02:33Hedgehog Signaling Pathway
01:29Bone Formation by Intramembranous Ossification
The process begins when mesenchymal cells in the embryonic skeleton gather together and differentiate into osteogenic cells, which then develop into ...