성장과 분화를 조절하는 인자인 myostatin은 포유류에서 주로 골격근에 분포하며 근육성장을 억제하는 것으로 알려져 있다. Myostatin은 포유류에서뿐만 아니라 어류에 있어서도 그 기능이 유사하며 본 연구에서는 넙치와 조피볼락 유래 재조합 myostatin 단백질을 생산하여 시마연어에 침지방법을 통해 처리하였다. 처리 결과 시마연어의 무게와 생화학 분석에서는 유의성이 나타날 정도의 증가는 없었지만 근(muscle) 조직학적 분석에서 넙치와 조피볼락 유래 재조합 myostatin prodomain에 의해 12주째에는 세포의 수가 증가하는 hyperplasia가 일어났으며 22주째에는 조피볼락 유래의 재조합 myostatin prodomain을 처리한 군에서만 hypertrophy가 일어났다. 결론적으로 어류 유래 재조합 myostatin prodomain이 시마연어 근육성장 시 hyperplasia와 hypertrophy가 순차적으로 유도되는 것으로 확인되었다.
Myostatin (MSTN) belongs to the transforming growth factor-${eta}$ superfamily or growth and differentiation factor 8 (GDF-8), and functions as a negative regulator of skeletal muscle development and growth. Previous studies in mammals have suggested that myostatin knock-out increased muscle mass and decreased fat content compared to those of the wide type. Recently, several studies on myostatin have beenconducted on the block myostatin signal pathway with myostatin antagonists and the MSTN regulation with RNAi to control myostatin function. This study was performed to analyze growth and muscle alteration of Oncorhychus masou by treatment with recombinant myostatin prodomains derived from fish. We designed myostatin prodomains derived from P. olivaceus (pMALc2x-poMSTNpro) and S. schlegeli (pMALc2x-sMSTNpro) in a pMALc2x expression vector, and then purified the recombinant proteins using affinity chromatography. The purified recombinant proteins were treated in O. masou through an immersion method. Recombinant protein treated groups did not show a significant difference in weight, protein, or lipid composition compared to the control. However, there was a difference in the average number and area for histological analyses in the muscle fiber. At twelve and twenty-two weeks from the initial treatment, there were differences in averagefiber number and area between the 0.05 mg/l treated-group and the control, but the numbers were similar to those of the control during the same time period. At twelve weeks, however, 0.2 mg/l treated-group had an increase in average fiber number and decrease in average fiber area compared to the control. At twenty-two weeks, the pMALc2x-sMSTNpro 0.2 mg/l treated-group was induced and showed a decrease in average fiber number and increase in average fiber area. The results between twelve and twenty-two weeks showed that the fiber numbers had decreased, whereas average fiberarea had increased due to sMSTNpro. It is understood that the sMSTNpro induced only hyperplasia at twelve weeks, after which it induced hypertrophy. Recombinant myostatin prodomains derived from fish may induce hyperplasia and hypertrophy in O. masou depending upon the time that has elapsed.
