Cot kinase promotes Ca2+ oscillation/calcineurin-independent osteoclastogenesis by stabilizing NFATc1 protein

Mol Cell Biol. 2012 Jul;32(14):2954-63. doi: 10.1128/MCB.05611-11. Epub 2012 May 21.


Osteoclasts are multinuclear bone-resorbing cells formed by the fusion of monocyte/macrophage-lineage precursor cells. Activation of the transcription factor NFATc1 (nuclear factor of activated T cells c1) by the receptor activator of NF-κB ligand (RANKL) is critical for osteoclast differentiation. In our previous report (Y. Kuroda, C. Hisatsune, T. Nakamura, K. Matsuo, and K. Mikoshiba. Proc. Natl. Acad. Sci. U. S. A. 105:8643, 2008), we demonstrated that osteoblasts induce osteoclast differentiation via Ca(2+) oscillation/calcineurin-dependent and -independent NFATc1 activation pathways; however, the mechanism underlying the latter remained unclear. Here we show that Cot, a serine/threonine kinase also known as tumor progression locus 2 (Tpl-2), directly phosphorylates all Ca(2+)/calcineurin-regulated NFAT family members (NFATc1 through NFATc4) and increases their protein levels. Moreover, Cot activity in osteoclasts was enhanced via cell-cell interaction with osteoblasts, and Cot promoted Ca(2+) oscillation/calcineurin-independent osteoclastogenesis by increasing NFATc1 stability through phosphorylation. We propose that NFAT activation in vivo occurs via phosphorylation-induced protein stabilization, even in the absence of Ca(2+) oscillation and calcineurin activity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Base Sequence
  • Bone Resorption / genetics
  • Bone Resorption / metabolism
  • Calcineurin / metabolism
  • Calcium Signaling
  • Cell Communication
  • Cell Differentiation
  • DNA Primers / genetics
  • MAP Kinase Kinase Kinases / deficiency
  • MAP Kinase Kinase Kinases / genetics
  • MAP Kinase Kinase Kinases / metabolism*
  • Mice
  • Mice, 129 Strain
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Mutagenesis, Site-Directed
  • NFATC Transcription Factors / genetics
  • NFATC Transcription Factors / metabolism*
  • Osteoblasts / metabolism
  • Osteoclasts / cytology*
  • Osteoclasts / metabolism*
  • Phosphorylation
  • Protein Stability
  • Proto-Oncogene Proteins / deficiency
  • Proto-Oncogene Proteins / genetics
  • Proto-Oncogene Proteins / metabolism*
  • RANK Ligand / metabolism
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism


  • DNA Primers
  • NFATC Transcription Factors
  • Nfatc1 protein, mouse
  • Proto-Oncogene Proteins
  • RANK Ligand
  • Recombinant Proteins
  • Tnfsf11 protein, mouse
  • MAP Kinase Kinase Kinases
  • Map3k8 protein, mouse
  • Calcineurin