Sardine procalcitonin amino-terminal cleavage peptide has a different action from calcitonin and promotes osteoblastic activity in the scales of goldfish
2017
Kase, Yoichi | Ikari, Takahiro | Sekiguchi, Toshio | Sato, Masayuki | Ogiso, Shouzo | Kawada, Tsuyoshi | Matsubara, Shin | Satake, Honoo | Sasayama, Yūichi | Endo, Masato | Kitamura, Kei-ichiro | Hattori, Atsuhiko | Watanabe, Takushi X. | Maruyama, Yusuke | Watanabe, Yoshinari | Funahashi, Hisayuki | Kambegawa, Akira | Suzuki, Nobuo
The nucleotide sequence of a sardine preprocalcitonin precursor has been determined from their ultimobranchial glands in the present study. From our analysis of this sequence, we found that sardine procalcitonin was composed of procalcitonin amino-terminal cleavage peptide (N-proCT) (53 amino acids), CT (32 amino acids), and procalcitonin carboxyl-terminal cleavage peptide (C-proCT) (18 amino acids). As compared with C-proCT, N-proCT has been highly conserved among teleosts, reptiles, and birds, which suggests that N-proCT has some bioactivities. Therefore, both sardine N-proCT and sardine CT were synthesized, and their bioactivities for osteoblasts and osteoclasts were examined using our assay system with goldfish scales that consisted of osteoblasts and osteoclasts. As a result, sardine N-proCT (10⁻⁷M) activated osteoblastic marker enzyme activity, while sardine CT did not change. On the other hand, sardine CT (10⁻⁹ to 10⁻⁷M) suppressed osteoclastic marker enzyme activity, although sardine N-proCT did not influence enzyme activity. Furthermore, the mRNA expressions of osteoblastic markers such as type 1 collagen and osteocalcin were also promoted by sardine N-proCT (10⁻⁷M) treatment; however, sardine CT did not influence their expressions. The osteoblastic effects of N-proCT lack agreement. In the present study, we can evaluate exactly the action for osteoblasts because our scale assay system is very sensitive and it is a co-culture system for osteoblasts and osteoclasts with calcified bone matrix. Both CT and N-proCT seem to influence osteoblasts and osteoclasts and promote bone formation by different actions in teleosts.
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