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Bafilomycin A1 Attenuates Osteoclast Acidification and Formation, Accompanied by Increased Levels of SQSTM1/p62
Sipin Zhu1,2, Sarah L Rea3,4, Taksum Cheng5
1Department of Orthopaedics, The Second Affiliated Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, 325035, China.
Abstract:
Vacuolar proton pump H(+)-adenosine triphosphatases (V-ATPases) play an important role in osteoclast function. Further understanding of the cellular and molecular mechanisms of V-ATPase inhibition is vital for the development of anti-resorptive drugs specifically targeting osteoclast V-ATPases. In this study, we observed that bafilomycin A1, a naturally-occurring inhibitor of V-ATPases, increased the protein level of SQSTM1/p62, a known negative regulator of osteoclast formation. Consistently, we found that bafilomycin A1 diminishes the intracellular accumulation of the acidotropic probe lysotracker in osteoclast-like cells; indicative of reduced acidification. Further, bafilomycin A1 inhibits osteoclast formation with attenuation of cell fusion and multi-nucleation of osteoclast-like cells during osteoclast differentiation. Taken together, these data indicate that bafilomycin A1 attenuates osteoclast differentiation in part via increased levels of SQSTM1/p62 protein, providing further mechanistic insight into the effect of V-ATPase inhibition in osteoclasts.
Insights
Bafilomycin A1 inhibits osteoclast formation by reducing cellular acidification and increasing SQSTM1/p62 protein levels. This provides insight into developing new drugs targeting vacuolar proton pump (V-ATPase) activity in osteoclasts.
Area of Science:
- Cell Biology
- Biochemistry
- Pharmacology
Background:
- Vacuolar proton pump H(+)-adenosine triphosphatases (V-ATPases) are crucial for osteoclast function.
- Understanding V-ATPase inhibition mechanisms is key for developing anti-resorptive drugs targeting osteoclasts.
Purpose of the Study:
- To investigate the cellular and molecular effects of bafilomycin A1, a V-ATPase inhibitor, on osteoclast differentiation.
- To elucidate the role of SQSTM1/p62 in V-ATPase inhibition-mediated effects on osteoclasts.
Main Methods:
- Treatment of osteoclast-like cells with bafilomycin A1.
- Assessment of intracellular acidification using lysotracker.
- Quantification of SQSTM1/p62 protein levels.
- Evaluation of osteoclast formation, cell fusion, and multi-nucleation.
Main Results:
- Bafilomycin A1 treatment increased SQSTM1/p62 protein levels in osteoclast-like cells.
- Bafilomycin A1 reduced intracellular acidification, indicated by diminished lysotracker accumulation.
- Bafilomycin A1 inhibited osteoclast formation, attenuating cell fusion and multi-nucleation.
Conclusions:
- Bafilomycin A1 attenuates osteoclast differentiation partly through increased SQSTM1/p62 protein levels.
- These findings offer mechanistic insights into V-ATPase inhibition in osteoclasts, relevant for drug development.
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