The chicken pituitary-specific transcription factor pit-1 is involved in the hypothalamic regulation of pituitary hormones

Abstract

Pit-1 is a pituitary-specific POU-domain DNA binding factor, which binds to and trans-activates promoters of growth hormone-(GH), prolactin-(PRL) and thyroid stimulating hormone-beta-(TSHβ) encoding genes. Thyrotropin-releasing hormone (TRH) is located in the hypothalamus and stimulates TSH, GH and PRL release from the pituitary gland. In the present study, we successfully used the cell aggregate culture system for chicken pituitary cells to study the effect of TRH administration on the ggPit-1* (chicken Pit-1), GH and TSHβ mRNA expression in vitro. In pituitary cell aggregates of 11-day-old male broiler chicks the ggPit-1* mRNA expression was significantly increased following TRH administration, indicating that the stimulatory effects of TRH on several pituitary hormones are mediated via its effect on the ggPit-1* gene expression. Therefore, a semiquantitative RT-PCR method was used to detect possible changes in GH and TSHβ mRNA levels. TRH affected both the GH and TSHβ mRNA levels. The results of this in vitro study reveal that ggPit-1* has a role in mediating the stimulatory effects of TRH on pituitary hormones like GH and TSHβ in the chicken pituitary.

Genomic structure and molecular characterization of growth hormone and its expression response to different feed types in golden pompanoTrachinotus ovatus(Linnaeus, 1758)

“…These regulatory factors are thought to regulate the GH gene through synergistic interactions (Ma et al., ; Zhang et al., ). The regulatory factors Pit‐1a, GRE, TRE, ERE and HNF‐3 were also present in the promoter region of ToGH , and Pit‐1a binds to AT‐rich cis elements in the GH gene promoter to regulate gene expression (Massah et al., ; Ohkubo et al., ; Van As et al., ). The presence of several transcriptional elements at the GH promoter suggests that the expression of ToGH might be regulated by synergistic interactions of several regulatory factors.…”