Transcription of the human EAP1 gene is regulated by upstream components of a puberty-controlling Tumor Suppressor Gene network

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.

A system biology approach to identify regulatory pathways underlying the neuroendocrine control of female puberty in rats and nonhuman primates

“…Using ChIP assays, we observed that all four of these transcription factors are recruited to the KiSS1 promoter; immunohistofluorescence studies showed that they are present in kisspeptin neurons in vivo (Mueller et al , 2011). We further observed that EAP1 gene expression is also under dual transcriptional regulation imposed by TTF1 (trans-activation) and YY1 and CUX1 (repression), and that EAP1 itself appears to control its own expression via a negative auto-feedback loop mechanism (Mueller and others, 2012). Consistent with the general features of a transcriptional regulatory network, TTF1, YY1 and CUX1 associate with the EAP1 promoter region and are expressed in hypothalamic EAP1 neurons, indicating that they are physiologically involved in the control of EAP1 gene expression.…”

Polycomb represses a gene network controlling puberty via modulation of histone demethylaseKdm6bexpression

“…immortalized hypothalamic cells overexpressing EED. The ChIP procedure was carried out essentially as previously described (8,48,49). Supplementary…”

Enhanced at Puberty-1 (Eap1) Expression Critically Regulates the Onset of Puberty Independent of Hypothalamic Kiss1 Expression

“…Previous studies have demonstrated that Eap1 transactivates the GnRH promoter but represses the preproenkephalin promoter, inferring that it has a dual transcriptional activity [4]. In 2012, Mueller et al [19]. discovered that Eap1 was regulated by ttf1, cux1 , and yy1 .…”