Poster Presentation Annual Meetings of the Endocrine Society of Australia and Society for Reproductive Biology and Australia and New Zealand Bone and Mineral Society 2016

In-vivo behaviors of pre-osteoclasts in c-fms transgenic and knock-out medaka fish (#296)

Masahiro Chatani 1 2 , Kazushi Aono 2 , Masamichi Takami 1 , Akira Kudo 2
  1. Department of Pharmacology, School of Dentistry, Showa University, Shinagawa, Tokyo, Japan
  2. Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Yokohama, Kanagawa, Japan

In bone modeling or remodeling, osteoclasts recognize the bone resorption site, however, its mechanism in-vivo remains unknown. We have generated the osteoclast-specific transgenic medaka line showing the specific localization of osteoclasts on the neural and hemal arches, and the opg deficient medaka showing the over-induced osteoclasts on the vertebral body. Here, to study the behavior of pre-osteoclasts, we established c-fms knock-out and fosmid transgenic medaka fish. Our results showed the failure of bone resorption in c-fms-a but not c-fms-b knock-out medaka. To visualize c-fms-a positive cells, the c-fms-a fosmid-GFP transgenic medaka line was generated, showing that as same to neural and hemal arches, the c-fms-a positive cells were localized at the centrum column where no osteoclasts were attached in the wild-type fish. To visualize osteoclast differentiation, we generated the c-fms-a formid-GFP/TRAP promoter-DsRed double transgenic medaka line, indicating change of the fluorescent signal in a cell; from green to yellow and from yellow to red in the long-term time-lapse imaging for 2 days. Moreover, in the c-fms-a knock-out/c-fms-a fosmid-GFP/TRAP promoter-DsRed line, decrease of the number of TRAP positive but not c-fms-a positive cells was shown. Taken together, our data suggested the new regulation systems of osteoclast differentiation in-vivo: the site-specific block of osteoclast differentiation by OPG and pre-existence of pre-osteoclasts at the resorption site.