Guangdong Provincial Key Laboratory of Animal Nutritional Regulation, National Engineering Research Center for Breeding Swine Industry, Guangdong Provincial Key Laboratory of Agro-Animal Genomics and Molecular Breeding, College of Animal Science, South China Agricultural University, 483 Wushan Road, Guangzhou, 510642, China.
Jilin Provincial Key Laboratory of Animal Embryo Engineering, College of Animal Sciences, Jilin University, 5333 Xian Road, Changchun, 130062, China.
Mol Cell Endocrinol. 2020 Apr 15;506:110763. doi: 10.1016/j.mce.2020.110763. Epub 2020 Feb 19.
Pituitary growth hormone (GH) plays an essential role in processes of organism growth and metabolism. MicroRNA (miRNA) could also participate in diverse biological processes. However, the role of miRNA in the regulation of pituitary GH during the growth process remains unclear. In this study, we firstly confirmed that the second highly expressed pituitary miRNA (miR-709) significantly inhibited the GH synthesis and suppressed the viability of GH3 cells. The bioinformatics analysis and dual luciferase report system were used to ascertain the PRKCA is the direct target gene of miR-709, which is the coding gene of PKCα. Then the transcription and translation levels of Prkca were obvious reduced by the over-expression of miR-709 in GH3 cells, followed by the inhibition of the transcription factor (CREB1) of Gh1 gene and the ERK1/2 signaling pathway or the possible cross-talk signaling pathway (cAMP/PKA signaling pathway) detected by western blot, suggesting that ERK1/2 maybe an important factor involved in the GH3 cell viability mediated by PKCα. At last, GHRP6 increased PKCα and GH expression but reduced miR-709 expression in vitro and vivo assays, and this conclusion was further confirmed by the result of GHRP6 attenuated the inhibition of miR-709 on GH expression. These findings will provide new molecular mechanism on the regulation of pituitary GH.
垂体生长激素（GH）在机体生长和代谢过程中发挥着重要作用。微小 RNA（miRNA）也参与多种生物学过程。然而，miRNA 在生长过程中调节垂体 GH 的作用尚不清楚。在本研究中，我们首先证实，第二高表达的垂体 miRNA（miR-709）显著抑制 GH 的合成并抑制 GH3 细胞的活力。通过生物信息学分析和双荧光素酶报告系统确定 PRKCA 是 miR-709 的直接靶基因，即 PKCα 的编码基因。然后，通过在 GH3 细胞中转染 miR-709，明显降低 Prkca 的转录和翻译水平，进而抑制 Gh1 基因的转录因子（CREB1）和 ERK1/2 信号通路或通过 western blot 检测到的可能的交叉对话信号通路（cAMP/PKA 信号通路），提示 ERK1/2 可能是 PKCα 介导的 GH3 细胞活力的重要因素。最后，GHRP6 在体外和体内实验中增加了 PKCα 和 GH 的表达，降低了 miR-709 的表达，并且这一结论进一步被 GHRP6 减弱 miR-709 对 GH 表达抑制的结果所证实。这些发现将为垂体 GH 的调节提供新的分子机制。
