The Effect Of Pituitary Specific Transcription Factor-Pit-1 On Pituitary GH Gene Expression And Its Role In The Pathogenesis Of Growth Hormone Deficiency

Pituitary specific transcription factor —Pit-1 is critical for anterior pituitary embryogenesis and regulation of GH, PRL and TSH gene expression. GH secretion and synthesis in the anterior pituitary is under the control of hypothalamus. Nuclear transcription factor-Pit-1 is necessary for the regulation of pituitary GH gene expression by GHRH. Recent studies showed that all components of the central nervous system (CNS), particularly that of hypothalamus and pituitary are capable of producing cytokines and cytokine receptors. At present the studies of GH regulated by cytokines are focused on the body and cells levels, however no one had examined whether these cytokines could regulate pituitary GH gene expression and what is their relationship with Pit-1. This study is to investigate the regulatory roles of various factors(GHRH, IL-1β, IL-6 and TNF-α ) on pituitary GH gene expression, the role of Pit-1 in the regulation of GH gene expression by these factors and to screen pit-1 gene mutation in the patients with growth hormone deficiency(GHD) to find out the meaning of pit-1 gene mutation as the cause of GHD. Expression plasmid pGL₂-GH-Luc constructed by human pit-1 gene promoter and luciferase reporter gene was transfected or cotransfected with pit-1cDNA expression plasmid (PcDNA-pit-1cDNA) into GH₃ cells, then luciferase expression was surveyed after adding hGHRH and cytokines(IL-1 β , IL-6 and TNF- α ). At the same time of cotrasfection,pit-l gene antisense oligonucleotide(pit-1 OND) was added into the culture medium to supress translation of Pit-1, and the change of luciferase expression in the GH₃ cells was surveyed. To screen for pit-1 gene mutation in the...