LIS1 Regulates Osteoclastogenesis through Modulation of M-SCF and RANKL Signaling Pathways and CDC42

Area of Science:

• Cell Biology
• Bone Biology
• Molecular Biology

Background:

• LIS1 is a key regulator of microtubules and dynein motor complex.
• Previous studies showed LIS1 depletion attenuates osteoclastogenesis in vitro.
• The precise mechanisms underlying LIS1's role in osteoclastogenesis were unclear.

Purpose of the Study:

• To elucidate the role and underlying mechanisms of LIS1 in osteoclast progenitor survival and osteoclastogenesis.
• To investigate the impact of LIS1 deficiency on bone mass and osteoclast number in vivo.
• To explore LIS1's regulation of signaling pathways involved in osteoclast formation.

Main Methods:

• Conditional deletion of LIS1 in osteoclast progenitors in mice.
• In vitro mechanistic studies on osteoclast precursor cells.
• Analysis of cell cycle progression, apoptosis, and signaling pathway activation (ERK, JNK).
• Investigation of CDC42 activation and rescue experiments using constitutively active CDC42.

Main Results:

• Conditional deletion of LIS1 in mice resulted in increased bone mass and reduced osteoclast numbers.
• LIS1 deficiency accelerated apoptosis of osteoclast precursor cells but had minimal effect on cell cycle.
• LIS1 loss dysregulated M-CSF and RANKL signaling, preventing ERK activation while enhancing JNK activation.
• LIS1 deficiency abrogated M-CSF and RANKL-induced CDC42 activation, which was partially rescued by active CDC42.

Conclusions:

• LIS1 plays a critical role in regulating osteoclast progenitor cell survival.
• LIS1 modulates M-CSF and RANKL-induced signaling pathways, including ERK, JNK, and CDC42 activation.
• LIS1 deficiency leads to increased bone mass, highlighting its importance in bone homeostasis.