| Retinoic acid as the active metabolite of vitamin A, plays an important role in cell growth, differentiation and other processes. Micro RNAs(mi RNAs) as the important regulators in the body also play an important part in the secretion of pituitary hormone,such as sex hormone and growth hormone. However, it is not clear whether retinoic acid as small nutrient molecular influences the expression of pituitary mi RNAs and whether it effects pituitary growth hormone through mi RNAs. Therefore, this study aimed to explore the effect of retinoic acid on pituitary mi RNAs that related to growth regulation, which was to find the regulatory mechanism about pituitary growth hormone through mi RNAs.First, rat pituitary adenoma cells(GH3 cells) were chosen to screen out small nutrient molecules that have effect on pituitary growth hormone, and were respectively treated with different concentrations of arginine(50 μmol/L, 100 μmol/L, 200 μmol/L, 400 μmol/L, and800 μmol/L) or different concentrations of retinoic acid(0.1 μmol/L, 1 μmol/L and 10μmol/L). Second, real-time fluorescent quantitative PCR was used to detect the expression of pituitary growth related mi RNAs(mi R-141-3 p, mi R-7a-5p, mi R-375-3p and mi R-709)and GH gene. Then 4 weeks male Sprague-Dawley(SD) rats were fed with retinoic acid for5 weeks constantly and detected the same indexes of the cell experiments; Finally eukaryotic expression vectors of mi R-141-3p’s target gene SOCS7 and mi R-7a-5p’s potential target gene MKNK2 were build to study their functions on GH3 cells preliminarily.Results as follows:1. GH3 cells were treated 24 h with different concentrations of arginine, then we found that the expression of mi R-375-3p were significantly incresed in 800 μmol/L, mi R-7a-5p and mi R-709 in 400 μmol/L. At the same time, GH1 and PIT1 m RNA expression were promoted by arginine in 200 μmol/L.2. GH3 cells were treated 36 h with different concentrations of retinoic acid, then it showed that mi R-7a-5p and mi R-375-3p expression were significantly inhibited in 1μmol/L as well as mi R-709, while GH1 and PIT1 m RNA expression were significantly promoted. The expression of mi R-141-3p was significantly inhibited in 0.1 μmol/L.3. After feeding retinoic acid to the rats 5 weeks, we found that the content of serum IGF-1 was markedly increased, the m RNA expression of mi R-141-3p, mi R-7a-5p,mi R-375-3p and mi R-709 m RNA were suppressed, and RA has a certain role in promoting the GH1, PIT1 and CREB m RNA expression.4. Eukaryotic expression vectors of pc DNA3.1-SOCS7, pc DNA3.1-MKNK2 and pc DNA3.1-ABHD8 were successfully build, and we preliminary found the two genes of SOCS7 and MKNK2 could promote GH1 and PIT1 in GH3 cells.In brief, this study found that arginine could promote the expression of rat pituitary mi RNAs which related to regulate growth, retinoic acid inhibited these mi RNAs’ expression, but increased the expression of SOCS7 and MKNK2, which in turn, affected the level of GH. Howerer the mechanism about how retinoic acid affect the biogenesis of mi RNAs need further discussion. |
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