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Culture of Murine Embryonic Metatarsals: A Physiological Model of Endochondral Ossification
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Jansen's Disease: Bone Abnormalities Beyond Chondrodysplasia
Renata C Pereira1, Anne M Delany2, Monica Reyes3
1Pediatric Nephrology, UCLA, Geffen School of Medicine, Los Angeles, CA 90095-8347, USA.
The Journal of Clinical Endocrinology and Metabolism
|February 14, 2025
Summary
Jansen metaphyseal chondrodysplasia (JMC) patients with the H223R-PTH1R mutation exhibit bone irregularities and abnormal osteocyte protein expression. These findings highlight the osteocyte as a potential therapeutic target for JMC.
Area of Science:
- Skeletal biology
- Pediatric endocrinology
- Genetic bone disorders
Background:
- Jansen metaphyseal chondrodysplasia (JMC) is a rare skeletal dysplasia.
- It is caused by activating mutations in the parathyroid hormone receptor 1 (PTH1R) gene.
- The H223R-PTH1R mutation leads to constitutive receptor activation, affecting bone development.
Purpose of the Study:
- To investigate bone microarchitecture, formation, and protein expression in pediatric JMC patients.
- To analyze the cellular and molecular consequences of the H223R-PTH1R mutation in bone.
Main Methods:
- Iliac crest bone biopsies were obtained from two male JMC patients and nine healthy controls.
- Histomorphometry, immunohistochemistry, and histologic analyses were performed.
- Specific proteins like PTH1R, DMP1, FGF23, and sclerostin were examined.
Main Results:
- JMC patients showed irregular bone architecture, increased osteoid, and delayed maturation.
- Osteocytes displayed abnormal morphology with osteoid accumulation in lacunae and canaliculi.
- Increased PTH1R expression was observed, alongside enhanced FGF23 and diminished sclerostin staining.
Conclusions:
- The H223R-PTH1R mutation causes significant bone structural and cellular abnormalities in JMC.
- Osteocyte dysfunction is a key feature, suggesting osteocytes as a therapeutic target.
- Further research is needed to explore therapeutic strategies targeting osteocytes for JMC treatment.
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