Determination of Calcium Sensing Receptor in the Scales of Goldfish and Induction of Its mRNA Expression by Acceleration Loading

It is known that the teleost scale regenerates after being removed. We previously reported that the osteogenesis in regenerating scales was very similar to that in calvarial bone, which suggests that regenerating scale can be used as a model for osteogenesis. In the present study, we determine calcium sensing receptor (CaSR) cDNA from the regenerating scales of goldfish. The determined partial sequence was coded as a 258-amino acid protein. The amino acid identity of this receptor to teteost CaSRs is 89 to 96%, lizard CaSR is 82%, and mammalian CaSR is 83 to 84%. These results indicate that CaSR is highly conserved in fish, lizard and mammals. Then, to examine the role of CaSR in bone metabolism, effect of acceleration loading (3 G) by vibration on the expression of CaSR mRNA in the regenerating scales of goldfish was investigated. We found that CaSR mRNA expression increased after acceleration loading by vibration in the regenerating scales. Significant difference between control and treatment group was observed at 6 and 24 h of incubation. Our cloned CaSR appears to act for the metabolism of bone in the regenerating scales. This is the first demonstration, to our knowledge, of an effect of hyper-loading on the induction of CaSR mRNA expression of hard tissues.