Detection of osteoclastic cell-cell fusion through retroviral vector packaging

Takako Kondo, Kyoji Ikeda, Koichi Matsuo

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)


Cell-cell fusion generates multinucleated cells such as osteoclasts in bone, myotubes in muscle, and trophoblasts in placenta. Molecular details governing these fusion processes are still largely unknown. As a step toward identification of fusogenic genes, we tested the concept that retroviral vectors can be packaged as a result of cell-cell fusion. First, we introduced replication-deficient retroviral vectors expressing mCAT-1, which mediates fusogenic interaction with the retroviral envelope protein Env, into Chinese hamster ovary (CHO) cells to generate vector cells. Plasmids expressing virion proteins Gag, Pol, and Env were introduced into a separate culture of CHO cells to generate packaging cells. Co-culturing vector and packaging cells resulted in production of infectious retroviruses carrying the mCAT-1 gene as a consequence of cell-cell fusion. Second, we introduced a retroviral vector into primary osteoclast precursors and co-cultured them with established osteoclast precursor RAW264.7 cells, which turned out to harbor packaging activity. Packaged retroviral vector was detected in culture supernatants only where the osteoclast differentiation factor receptor activator for NF-κB ligand (RANKL) induced fusion between these two cell types. These data suggest that retrovirus production can occur as a result of cell-cell fusion. This provides a novel approach for isolating and characterizing fusogenic genes using retroviral expression vectors.

Original languageEnglish
Pages (from-to)1120-1126
Number of pages7
Issue number5
Publication statusPublished - 2004 Nov


  • Fusion
  • Osteoclasts
  • Retrovirus

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Physiology
  • Histology


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