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Updated: Jun 26, 2025

A RANKL-based Osteoclast Culture Assay of Mouse Bone Marrow to Investigate the Role of mTORC1 in Osteoclast Formation
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RUFY4 deletion prevents pathological bone loss by blocking endo-lysosomal trafficking of osteoclasts

Minhee Kim1, Jin Hee Park1,2, Miyeon Go1

  • 1Department of Life Science, Ewha Womans University, Seoul, 03760, South Korea.

Bone Research
|May 14, 2024
PubMed

Insights

RUN and FYVE domain-containing protein 4 (RUFY4) is crucial for osteoclast function and bone resorption. Its absence protects against bone loss by regulating lysosomal trafficking, offering a potential therapeutic target for osteoporosis.

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Bone Biology

Background:

  • Osteoclasts degrade bone matrix via protease secretion from lysosomes.
  • Mechanisms of lysosomal trafficking and secretion in osteoclasts are not fully understood.

Purpose of the Study:

  • To investigate the role of RUFY4 in osteoclastogenesis and bone resorption.
  • To elucidate the molecular mechanisms of RUFY4 in lysosomal trafficking.

Main Methods:

  • GeneChip analysis to identify upregulated genes during osteoclastogenesis.
  • Phenotypic analysis of Rufy4-deficient mice.
  • Assessment of osteoclast function and bone resorption assays.
  • Investigation of lysosomal maturation, trafficking, and protease secretion.

Main Results:

  • RUFY4 is upregulated during osteoclastogenesis.
  • Rufy4 deficiency leads to high trabecular bone mass and impaired osteoclast function.
  • RUFY4 is essential for acidic maturation and membrane trafficking of secondary lysosomes.
  • RUFY4 mediates late endosome-lysosome fusion via Rab7 and LAMP2 interaction.
  • Rufy4-deficient mice are protected from LPS- and ovariectomy-induced bone loss.

Conclusions:

  • RUFY4 is a novel regulator of osteoclast activity.
  • RUFY4 mediates endo-lysosomal trafficking essential for bone resorption.
  • RUFY4 represents a potential therapeutic target for osteoporosis and other bone-loss diseases.

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