mu-Calpain regulates receptor activator of NF-kappaB ligand (RANKL)-supported osteoclastogenesis via NF-kappaB activation in RAW 264.7 cells

J Biol Chem. 2005 Aug 19;280(33):29929-36. doi: 10.1074/jbc.M414600200. Epub 2005 Jun 13.

Abstract

To clarify the role of calpain in the receptor activator of NF-kappaB ligand (RANKL)-supported osteoclastogenesis, RANKL-induced calpain activation was examined by using murine RAW 264.7 cells and bone marrow-derived monocyte/macrophage progenitors. We found that calpain activity increased in response to RANKL in both cell types based on alpha-spectrinolysis and that mu-calpain, rather than m-calpain, was activated during RANKL-supported osteoclastogenesis in RAW 264.7 cells. Overexpression of mu-calpain clearly augmented RANKL-supported osteoclastogenesis in RAW 264.7 cells, thereby implicating its pivotal role in this process. Cell-permeable calpain inhibitors, including calpastatin and calpeptin, were sufficient to suppress RANKL-supported osteoclastogenesis based on decreased expression of the osteoclastogenic marker, matrix metalloproteinase 9, and the generation of tartrate-resistant acid phosphatase-positive multinucleated cells in both cell types. Calpain inhibitors suppressed NF-kappaB activation via inhibition of the cleavage of inhibitor of NF-kappaB(IkappaBalpha)in RAW 264.7 cells. Taken together, our findings suggest that mu-calpain is essential to the regulation of RANKL-supported osteoclastogenesis via NF-kappaB activation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Calpain / physiology*
  • Carrier Proteins / pharmacology*
  • Cell Differentiation
  • Cell Line
  • I-kappa B Proteins / metabolism
  • Macrophages / cytology
  • Membrane Glycoproteins / pharmacology*
  • Mice
  • NF-KappaB Inhibitor alpha
  • NF-kappa B / physiology*
  • Osteoclasts / physiology*
  • RANK Ligand
  • Receptor Activator of Nuclear Factor-kappa B

Substances

  • Carrier Proteins
  • I-kappa B Proteins
  • Membrane Glycoproteins
  • NF-kappa B
  • Nfkbia protein, mouse
  • RANK Ligand
  • Receptor Activator of Nuclear Factor-kappa B
  • Tnfrsf11a protein, mouse
  • Tnfsf11 protein, mouse
  • NF-KappaB Inhibitor alpha
  • Calpain
  • mu-calpain