Cytokines On The Pituitary Human Growth Hormone Gene Expression Regulation And Its Mechanism

During stressful challenge to the organism, CRH, ACTH and glucocorticoid are released from the hypothalamus, pituitary and adrenal to regulate the immune function. Meanwhile, other kind of the stressful hormone, such as growth hormone(GH) and prolactin(PRL) also increased. It is very interesting to investigate the roles and the regulatory mechanism of secretion for GH and PRL in stress. Recent studies demonstrate that cytokines generated by immune system are also expressed in hypothalamus and pituitary gland, and have significant impact on growth, differentiation and GH secretion of pituitary cells. These results prompt us to study whether cytokines influence synthesis of GH and their possible mechanism(s) involved. To address this question, we examined the effects of cytokines, such as IFN-γ,IL-1β,IL-6, IL-11, CNTF, TGF- β and activin on hGH gene expression (including in transcriptional and translational level) and possible mechanism(s) involved in rat pituitary tumour cells, GH3 and MtT/S, using the enzyme immunoassay (EIA) and the method of stably transfection of the hGH gene promoter fused to a luciferase reporter gene at cellular and genomic molecular level.1. cloning 484-luc2 plasmid and establishing stabe transfection GH3 and MtT/S cell lines. The hGH gene promoter (-484~+30 bp) was inserted into luciferase reporter gene vector pGL3-Basic. The recombinant plasmid (484-luc2) contains hGH gene promoter (-484~+30bp) and luciferase fused gene. 484-luc2 was transfected into rat pituitary tumour cells, GH3 and MtT/S by liposome transfection method. After screening with G418, a kind of screening drug, stable transfection GH3 and MtT/S cell lines which can expressed stably luciferase were obtained.2. The effects of cytokines on GH secretion and synthesis by...