본 연구에서는 유전자 발현에 중요한 조절 역할을 하는 DNA 메틸화를 식이성 폴리페놀의 하나인 녹차의 대표적인 추출물 EGCG로 억제하였을 때 C2C12 myoblast 세포에 일어나는 현상을 살펴보았다. 그 결과 smooth muscle의 지표인 transgelin, smooth muscle ${alpha}-actin$ mRNA와 단백질이 현저히 증가함을 보였고, 형태학적으로도 smooth muscle의 전형적인 모습을 보였다. 식이에 포함된 DNA 메틸화 억제제인 EGCG가 C2C12 myoblast를 smooth muscle로 분화를 유도하였으며, 암 예방 차원에서의 EGCG의 역할 외에 혈관질환과 같은 smooth muscle에 관련된 예방과 치료차원에서 EGCG의 역할이 있을 것으로 사료된다. 본 연구는 C2C12 myoblast를 smooth muscle로 유도하는 결정적인 신호전달 역할을 하는 유전자에 대한 연구는 수행하지 못하였다. 따라서 EGCG에 의해 변화되는 유전자에 대한 기전연구가 필요하다고 하겠다.
In the present investigation, we studied the modulating effects of (-)-epigallocatechin-3-gallate(EGCG) on the differentiation of mouse C2C12 myoblasts. We found that the strong inhibitory effect of EGCG on DNA methyltransferase-mediated DNA methylation induced transdifferentiation of C2C12 myoblasts into smooth muscle cells demonstrated by both morphological changes and immunofluorescent staining. C2C12 myoblasts treated with EGCG for 4 days expressed smooth muscle ${alpha}-actin$ protein. Real-time PCR data revealed that smooth muscle ${alpha}-actin$ mRNA was induced by EGCG treated C2C12 myoblasts in a concentration-dependent manner. Smooth muscle ${alpha}-actin$ mRNA concentration increased 330% and 490% after 2 and 3 days of 50 ${mu}M$ of EGCG treatment. The expression of another smooth muscle marker, transgelin, mRNA was also increased up to 9-fold by 4 days of EGCG treatment compared with control in a concentration-dependent manner. These results suggested that C2C12 enables to transdifferentiate into smooth muscle when gene expression patterns are changed by the inhibition of DNA methylation induced by EGCG. In conclusion, transdifferentiation of C2C12 myoblasts into smooth muscle is resulted from the modulating effects of EGCG on DNA methylation which subsequently results in changing the expression pattern of several genes playing a critical role in the differentiation of C2C12 myoblasts.
