| Growth hormone(GH)is a protein hormone synthesized in the pituitary gland which can affect almost all tissues,regulate cell metabolic and have lipolytic effect.When the growth hormone is secreted too much,it will cause giant disease and acromegaly;when the growth hormone is secreted little,it will cause dwarfism.Therefore,it is of great significance to keep GH at a stable and appropriate level to maintain physiological homeostasis.The synthesis of GH is mainly controlled by growth hormone regulating hormone(GHRH)and growth hormone release-inlease-inhibiting hormone(GHRIH).Besides these two classic regulators,various neurotransmitters,hormones and cytokines also affect GH secretion.Therefore,it is important to clarify the molecular mechanism of growth hormone regulation.Circular RNA(circRNA)is a type of endogenous long-chain non-coding RNA.A large number of studies have proved that circRNA has different biological functions in different species and cell lines.Among them,the most studied is it can act as a ceRNA.It can absorb a large number of miRNAs through the miRNA response element(MRE)and prevent them from binding to the target gene,and then negatively regulate the biological function of the miRNA.However,whether circRNA participates in the regulation of GH and affects the growth and development of mammals is still unknown.In this study,the dual luciferase reporter system and transfection experiments were used to analyze the relationship between miR-543-5p and GH.Bioinformatics was used to screen out the circRNAs that bind to miR-543-5p in the adenohypophysis of rats,named circAgtpbp1.The circAgtpbpl overexpression plasmid was constructed and siRNA was designed to analyze the potential effect of circAgtpbp1 on the GH secretion in pituitary.The dual luciferase reporter system and RIP experiment verified the interaction of circAgtpbp1 with miR-543-5p.Our results indicate:1.miR-543-5p can inhibit the secretion of GH in rat pituitary.In different tissues of rats,miR-543-5p was highly expressed in pituitary,and miR-543-5p was highly expressed in pituitary of sexually mature rats.Dual luciferase reporter system and miR-543-5p transfection experiment proved that miR-543-5p can inhibit the GH secretion in rat pituitary.2.circAgtpbpl can be used as a molecular sponge for miR-543-5p to regulate the GH secretion in rats.We screened through bioinformatics to circAgtpbpl with miR-543-5p targeting binding site for subsequent experiments.It was confirmed by sequence alignment that circAgtpbp1 originated from rat chromosome 17,and circAgtpbp1 was identified by using PCR,agarose gel electrophoresis,and sanger sequencing.Afterwards,by knocking down and overexpressing circAgtpbp1,the expression level of Ghl gene and the secretion level of GH hormone were affected,indicating that circAgtpbpl has potential regulation ability on GH secretion.The RIP experiment and the dual luciferase reporter system proved that circAgtpbp1 has a targeting relationship with miR-543-5p,and the rescue experiment proved that circAgtpbpl can regulate the secretion of GH hormone by adsorbing miR-543-5pIn summary,this study analyzed circAgtpbpl regulating the GH secretion in the rat pituitary through competitively binding to miR-543-5p,analyzed the way in which circRNA in rat pituitary participates in the regulation of animal growth and development,provided the theoretical support for further analyzing the regulation of pituitary hormone secretion mechanism. |
