The signaling adapter protein DAP12 regulates multinucleation during osteoclast development

Area of Science:

• Immunology
• Cell Biology
• Bone Biology

Background:

• Osteoclasts are crucial for bone resorption, originating from myeloid precursors.
• The signaling adapter protein DAP12 (DNAX-activating protein of 12 kDa) transmits signals in myeloid cells via DAP12-associated receptors (DARs).
• Understanding DAP12's role in osteoclast development is essential for bone biology research.

Purpose of the Study:

• To investigate the function of DAP12 signaling in murine osteoclasts.
• To identify DAP12-associated receptors (DARs) expressed by osteoclasts.
• To clarify the role of DAP12 in osteoclast formation and bone remodeling.

Main Methods:

• Analysis of osteoclasts from DAP12-deficient and control mice in vitro and in vivo.
• Identification of DARs using RT-PCR.
• Bone density analysis via microcomputed tomography.
• Functional rescue experiments by retroviral reconstitution of DAP12.

Main Results:

• DAP12-deficient mice exhibit increased bone mass.
• DAP12 deficiency in vitro leads to mononuclear osteoclast-like cells that fail to multinucleate.
• These mononuclear cells exhibit osteoclast markers and resorption activity, albeit reduced.
• Restoration of DAP12 rescues multinucleation, and its stimulation increases osteoclast formation.

Conclusions:

• DAP12 signaling is critical for the formation of multinucleated osteoclasts.
• DAP12 and its associated receptors play a significant role in regulating bone remodeling.
• This study reveals a novel function for DAP12 in osteoclast biology.