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Rab32 and Rab38 maintain bone homeostasis by regulating intracellular traffic in osteoclasts.
Kanako Tokuda1, Shiou-Ling Lu2, Zidi Zhang2
1Graduate School of Frontier Biosciences, Osaka University.
Cell Structure and Function
|October 4, 2023
Summary
Rab32 and Rab38 proteins are essential for osteoclast function and bone resorption. Their absence in knockout mice leads to thickened bones and abnormal bone growth, highlighting their role in maintaining skeletal homeostasis.
Area of Science:
- Cell Biology
- Bone Biology
- Molecular Biology
Background:
- Osteoclasts are critical for bone resorption and homeostasis.
- Rab38 protein expression increases during osteoclast differentiation from macrophages.
- The roles of Rab32 and Rab38 in osteoclasts remained unclear.
Purpose of the Study:
- To investigate the function of Rab32 and Rab38 in osteoclast biology.
- To determine the impact of Rab32 and Rab38 deficiency on bone homeostasis in vivo.
Main Methods:
- Generated Rab32/Rab38 double knockout (DKO) mice.
- Analyzed osteoclast differentiation and function in vitro.
- Assessed bone structure and resorption markers in vivo using micro-CT, histomorphometry, and serum analysis.
Main Results:
- DKO osteoclasts showed normal differentiation but reduced bone resorption activity and secretion of key enzymes.
- Plasma membrane localization of V-ATPase was impaired in DKO osteoclasts.
- DKO mice exhibited thickened trabecular bones, reduced bone resorption markers, and developed hyperostosis and kyphosis with age.
Conclusions:
- Rab32 and Rab38 are crucial for osteoclast function, likely by supporting intracellular transport pathways.
- These proteins play a significant role in maintaining normal bone homeostasis.
- Dysregulation of Rab32 and Rab38 contributes to skeletal abnormalities.
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