Understanding molecular mechanism of osteoclast formation and function

Tuesday, October 25, 2011 — Poster Session II
Noon – 2:00 p.m.	Natcher Conference Center	NIAID	PROTEOM-1

Authors

• E An
• S Park
• R Germain
• A Nita-Lazar

Abstract

Osteoclasts are specialized in bone resorption and most skeletal diseases are due to excess osteoclastic activity causing pain and fracture. Therefore, it is important to understand molecular mechanism of osteoclast formation and function to control their activity. In vitro, mouse monocyte-macrophage cell line, RAW 264.7 is often used with receptor activator of nuclear factor kappa B ligand (RANKL) to form osteoclasts and tartrate resistant acid phosphatase (TRAP) staining is usually applied to examine osteoclast formation. However, not 100% of precursors form osteoclasts upon RANKL treatment. 3-Plex SILAC is used to examine proteomes of osteoclast precursors, osteoclasts, and TRAP + cells. In this study, 2,651 proteins with more than 2 peptides were identified and around 80% of these proteins were quantified. Although formation of both osteoclasts and TRAP+ cells are the results of RANKL treatments, their proteomes are found to be differently regulated confirming that it is necessary to separate these cell types to understand the mechanism of osteoclast formation. This study suggests that osteoclasts save energy by controlling cell cycle, gene expression, and protein synthesis while function of mitochondria is compromised. Anti-apoptosis is favored and proteins involved in integrin activation are found to be upregulated in osteoclasts than precursors.

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