Analysis of relationship between proteins and external stimuli on bone formation/resorption

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In teleostei, Ca metabolism is regulated via scale rather than bone, especially in case that rapid mobilization of Ca is required. The first porpose of this study is to determine whether scale can be a model for the research exploring relationship between mammalian osteoblast and osteoclast. In unexposed parts of scale, ALP-positive cells, viz osteoblasts, were located in lamellas between the first to third ridge at the bottom, and cells beyond the third ridge showed nuclei-nuclei linkage without ALP- and TRAP-activity. In exposed parts, co-localization of ALP-positive and TRAP-positive cells (osteoclasts) were observed at the lateral periphery, indicating that enlargement toward the lateral direction was strictly regulated. TRAP-positive cells were induced at pits. In unexposed parts of regenerating scales, TRAP-activity was enhanced at the lateral periphery and was positive with an osteocytic canaliculi shape in lamellas adjacent to ALP-positive cells. On the other hand, lateral line … More tube was surrounded both by ALP-positive and TRAP-positive cells. To maintain the wall of lateral line tube very thin is essential to introduce movement of environmental water to lateral line nerve terminal. It is also considered that to explore how lateral line tube and nerve function is a good model for exploring development of peripheral sensory nerve. We also found that, for the maintenace of lateral line tube, notch, inducers of apoptosis, as well as inhibitors of apoptosis, etc. were up-regulated. Aside from mammalians, these full sequence was yet known, so that we cloned these signals. Furthermore, we confirmed that these ALP-positive and TRAP-positive cells showed response to hormones similar with mammalian osteoclasts/osteoblasts. For the prevention of osteopososis, we have been trying to utilize VitK2. We found that Vit K2 inhibit proliferating mammalian osteoblasts and promote differentiating into osteocyte.s. Scale ALP-positive cells showed similar response to Vit K2. Thus,Both ALP- and TRAP-positive cells displayed similarity to mammalian osteoblast/osteoclast in response to externalstimuli. Teleost scales are transparent to be a good model for studying osteoblast/osteocyte/osteoclast inter/intracellular relationship in vivo and/or as whole mount culture. Less