Cobalt protoporphyrin represses osteoclastogenesis through blocking multiple signaling pathways

Yuka Yashima, Kuniaki Okamoto, Eiko Sakai, Mayumi Iwatake, Yutaka Fukuma, Kazuhisa Nishishita, Takayuki Tsukuba

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)


Cobalt protoporphyrin (CoPP) is a metallo-protoporphyrin that works as a powerful inducer of heme oxigenase-1 (HO-1) in various tissues and cells. Our recent studies have demonstrated that induction of HO-1 by several reagents inhibited differentiation and activation of osteoclasts (OCLs), which are multinucleated bone resorbing cells. However, the effects of CoPP on osteoclastogenesis remain to be elucidated. In this study, we report that CoPP inhibits receptor activator of nuclear factor κB ligand (RANKL)-induced OCL formation in a dose dependent manner. Importantly, CoPP had little cytotoxicity, but rather enhanced cell proliferation of OCLs. CoPP suppressed the protein levels of nuclear factor of activated T cells cytoplasmic-1 (NFATc1) as well as those of OCLs markers such as Src and cathepsin K, which are transcriptionally regulated by NFATc1 in mature OCLs. Western blot analyses also showed that CoPP abolished RANKL-stimulated phosphorylation of several major signaling pathways such as IκB, Akt, ERK, JNK and p38 MAPKs in OCL precursor cells. Thus, our results show that CoPP represses osteoclastogenesis through blocking multiple signaling pathways.

Original languageEnglish
Pages (from-to)725-732
Number of pages8
Issue number4
Publication statusPublished - Aug 27 2015
Externally publishedYes


  • Cobalt protoporphyrin
  • Hemeoxigenase-1
  • Osteoclasts

ASJC Scopus subject areas

  • Biomaterials
  • Biochemistry, Genetics and Molecular Biology(all)
  • Agricultural and Biological Sciences(all)
  • Metals and Alloys


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