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Updated: Aug 14, 2026
The Soft Agar Colony Formation Assay
Published on: October 27, 2014
Cbfa1-independent decrease in osteoblast proliferation, osteopenia, and persistent embryonic eye vascularization in
Masaki Kato1, Millan S Patel, Regis Levasseur
1Department of Molecular and Cellular Biology and Medicine, Baylor College of Medicine, Houston, TX 77030, USA.
Abstract:
The low-density lipoprotein receptor-related protein (Lrp)-5 functions as a Wnt coreceptor. Here we show that mice with a targeted disruption of Lrp5 develop a low bone mass phenotype. In vivo and in vitro analyses indicate that this phenotype becomes evident postnatally, and demonstrate that it is secondary to decreased osteoblast proliferation and function in a Cbfa1-independent manner. Lrp5 is expressed in osteoblasts and is required for optimal Wnt signaling in osteoblasts. In addition, Lrp5-deficient mice display persistent embryonic eye vascularization due to a failure of macrophage-induced endothelial cell apoptosis. These results implicate Wnt proteins in the postnatal control of vascular regression and bone formation, two functions affected in many diseases. Moreover, these features recapitulate human osteoporosis-pseudoglioma syndrome, caused by LRP5 inactivation.
Insights
Low-density lipoprotein receptor-related protein 5 (Lrp5) is crucial for bone formation and eye development. Its absence in mice leads to low bone mass and persistent embryonic eye vascularization, mimicking human conditions.
Area of Science:
- Molecular Biology
- Developmental Biology
- Genetics
Background:
- Low-density lipoprotein receptor-related protein 5 (Lrp5) is a known Wnt signaling coreceptor.
- Wnt signaling pathways are critical for various developmental processes.
- Dysregulation of Wnt signaling is implicated in bone disorders and vascular abnormalities.
Purpose of the Study:
- To investigate the function of Lrp5 in postnatal bone formation and eye development.
- To elucidate the role of Lrp5 in Wnt signaling within osteoblasts.
- To establish a mouse model for studying Lrp5-related human diseases.
Main Methods:
- Targeted gene disruption of Lrp5 in mice.
- In vivo and in vitro analyses of bone mass and osteoblast function.
- Assessment of eye vascularization and endothelial cell apoptosis.
Main Results:
- Lrp5-deficient mice exhibit a low bone mass phenotype evident postnatally.
- Reduced osteoblast proliferation and function were observed in Lrp5-deficient mice, independent of Cbfa1.
- Lrp5 deficiency resulted in persistent embryonic eye vascularization due to impaired macrophage-induced endothelial cell apoptosis.
- Lrp5 is expressed in osteoblasts and is essential for optimal Wnt signaling.
Conclusions:
- Lrp5 is indispensable for postnatal bone formation and vascular regression.
- Wnt proteins, mediated by Lrp5, play a significant role in regulating bone density and vascular development.
- Lrp5 inactivation recapitulates key features of human osteoporosis-pseudoglioma syndrome, highlighting its clinical relevance.
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