Kisspeptin, the product of the KiSS1 gene, has emerged as a key component of the mechanism by which the hypothalamus controls puberty and reproductive development. It does so by stimulating the secretion of gonadotropin releasing hormone (GnRH). Little is known about the transcriptional control of the KiSS1 gene. Here we show that a set of proteins postulated to be upstream components of a hypothalamic network involved in controlling female puberty regulates KiSS1 transcriptional activity. Using RACE-PCR we determined that transcription of KiSS1 mRNA is initiated at a single transcription start site (TSS) located 153–156 bp upstream of the ATG translation initiation codon. Promoter assays performed using 293 MSR cells showed that the KiSS1 promoter is activated by TTF1 and CUX1-p200, and repressed by EAP1, YY1, and CUX1-p110. EAP1 and CUX-110 were also repressive in GT1-7 cells. All four TFs are recruited in vivo to the KiSS1 promoter and are expressed in kisspeptin neurons. These results suggest that expression of the KiSS1 gene is regulated by trans-activators and repressors involved in the system-wide control of mammalian puberty.

No abstract

No abstract

Mammalian puberty is initiated by an increased pulsatile release of gonadotropin-releasing hormone (GnRH) from specialized neurons located in the hypothalamus. GnRH secretion is controlled by neuronal and glial networks, whose activity appears to be coordinated via transcriptional regulation. One of the transcription factors involved in this process is thought to be the recently described gene Enhanced at Puberty 1 (EAP1), which encodes a protein with dual transcriptional activity. In this study we used gene reporter and chromatin immunoprecipitation (ChIP) assays to examine the hypothesis that EAP1 expression is controlled by transcriptional regulators earlier postulated to serve as central nodes of a gene network involved in the neuroendocrine control of puberty. These regulators include Thyroid Transcription Factor 1 (TTF1), Yin Yang 1 (YY1) and CUX1, in addition to EAP1 itself. While TTF1 has been shown to facilitate the advent of puberty, YY1 (a zinc finger protein component of the Polycomb silencing complex) may play a repressive role. The precise role of CUX1 in this context is not known, but like EAP1, CUX1 can either activate or repress gene transcription. We observed that DNA segments of two different lengths (998 and 2744 bp) derived from the 5′-flanking region of the human EAP1 gene display similar transcriptional activity. TTF1 stimulates transcription from both DNA segments with equal potency, whereas YY1, CUX1, and EAP1 itself, behave as transcriptional repressors. All four proteins are recruited in vivo to the EAP1 5′-flanking region. These observations suggest that EAP1 gene expression is under dual transcriptional regulation imposed by a trans-activator (TTF1) and two repressors (YY1 and CUX1) previously postulated to be upstream components of a puberty-controlling gene network. In addition, EAP1 itself appears to control its own expression via a negative auto-feedback loop mechanism. Further studies are needed to determine if the occupancy of the EAP1 promoter by these regulatory factors changes at the time of puberty.