Study On The Effect Of MiR143 And MiR145 On C2C12 Differentiation

MicroRNA (miRNA)is a class of about 21-nucleotide-long noncoding small RNA, which can combine with 3’-UTR of the target gene to inhibit the translation of target genes or directly degrade the target genes. The number of miRNAs is limited, but they can regulate a lot of biological process, such as the growth and death of cell, the fate of cancer cell, the differentiation of nerve, cell metabolism and the differentiation of myoblast and adipocyte. Skeletal muscle is the biggest tissue of individual, the development of which is very complicated. The development of skeletal muscle can be regulated by not only the MRFs, but also the DNA methylation、histone modification and miRNAs. And miRNA regulate the differentiation of myoblast through the regulation of factors that involve in myoblast development. Canonical Wnt signal pathway has various effect on biological development, such as the cancer、fibrosis、osteogenesis. But more and more research found that canonical Wnt signal pathway can regulate the development of myoblast and the type of myofiber. However,The goal of our research is to study the effect of miR143 and miR145 on the differentiation of C2C12, and the Wnt signal pathway. The results is showing below:1. In the normal process of differentiation of C2C12, the expression of miR143 and miR145 is increase.2. Overexpression or lowexpression of miR143 and miR145 in C2C12 after the 4th day, the expression level of MyoG and MyoD will decrease significantly(P< 0.01). In the whole process of differentiation miR143 has little effect on the expression level of Myf5, but overexpression or lowexpression miR145 will significantly up-regulate the expression level of Myf5 (P<0.01). In the medium process of differentiation, the expression level of MRF4 was affected by overexpression of miR143 and miR145, but lowexpression of miR143 and miR145 has little effct on MRF4. The symbol genes of differentiation MyHC and ACTA1 has low expression level when overexpress miR143 and miR145, and lowexpression of miR 145 also inhibit the expression of MyHC. These results indicate that miR143 and miR145 has different regulation effect of C2C12 myoblast.3. miR143 can obviously inhibit the expression level of 4 type of muscle fiber, and especially the MyHC Ⅱ. Overexpression and lowexpression of miR145 will inhibit the expression level of 4 type of myofiber. Thus, miR143 can regulate the the processe of differentiation and the regulation of miR145 on 4 type of myofiber is not obvious.4. miR143 and miR145 regulate the canonical Wnt signal pathway mainly in the medium process of differentiation(Day2 to Day6), overexpression and lowexpression of miR143 and miR145 can significantly upregulate the expression level of main gene Axin2、LRP5 and β-catenin (P<0.01) and there is difference between miR143 and miR145 in regulatiou of Wnt signal pathway. And the expression level of the noncanonical Wnt member wnt5a decrease with ovepression miR143 and miR145, indicating that miR143 and miR145 can inhibit the noncanonical Wnt signal pathway in the process of myoblast differention.The above results shows that miR143 and miR145 can up-regulate the early myogenic regulation factors in early time during C2C12 cell differentiation. Our study also found the expression level of MyHC、ACTA1、MyoG and xxx were inhibited in the process of differention. Moreover miR143 and miR145 can inhibit myofiber type differentiation, and they can promote canonical Wnt signal pathway main gene LRP5、Axin2、and β-catenin. In our study, miR143 and miR145 cannot promote the differention of C2C12 as we expected, thus the effect of miR143 and miR145 on differention of C2C12 and the interaction with Wnt signal pathway need more deep research.