AMPKα1 negatively regulates osteoclastogenesis and mitigates pathological bone loss

Area of Science:

• Cell Biology
• Metabolism
• Bone Biology

Background:

• Osteoclasts are crucial for bone resorption, a process vital for skeletal homeostasis but implicated in diseases like osteoporosis.
• Osteoclast metabolism is a potential therapeutic target for osteolytic diseases.
• AMP-activated protein kinase α1 (AMPKα1), an energy sensor, is highly expressed in osteoclasts and influences their metabolic state during differentiation and activation.

Purpose of the Study:

• To investigate the role of AMPKα1 in osteoclastogenesis and bone resorption in vitro.
• To determine the impact of AMPKα1 deficiency on bone loss in vivo.

Main Methods:

• Utilized LysMcre/0AMPKα1f/f mice and control littermates (LysMcre/0) for in vitro osteoclast differentiation and bone resorption assays.
• Analyzed gene expression of osteoclast differentiation and fusion markers.
• Examined mitochondrial dynamics (Mfn2, DRP1) and mitochondrial content in AMPKα1-deficient osteoclasts.
• Assessed bone loss in vivo using Ctskcre/0AMPKα1f/f mice.

Main Results:

• AMPKα1 is upregulated during early osteoclastogenesis.
• Genetic deletion of AMPKα1 in osteoclasts resulted in enhanced differentiation, increased osteoclast number and size, and elevated bone resorption.
• AMPKα1 deficiency altered mitochondrial dynamics by upregulating Mfn2 and downregulating DRP1, leading to increased mitochondrial content.
• Ctskcre/0AMPKα1f/f mice exhibited significant bone loss in vivo, mirroring ovariectomy-induced bone loss.

Conclusions:

• AMPKα1 acts as a negative regulator of osteoclastogenesis and bone resorption.
• Depletion of AMPKα1 in osteoclasts promotes a bone loss phenotype.
• Targeting AMPKα1 in osteoclasts represents a potential therapeutic strategy for treating osteolytic bone diseases.