Twenty-four hours after transfection with EAP1-pGL3, C6 cells were treated with 1 and 10 nmestradiol or the vehicle (ethanol) as a control. 100 kb of the rEap1locus. Functional promoter assays showed that neither estradiol (E2) alone nor a combination of E2plus progesterone increases rEap1gene transcription. Similarly, E2administered to ovariectomized immature rats elicited a strong surge of LH but increased neither preoptic area nor MBHEap1mRNA levels. E2/progesterone-treated rats showed a massive elevation in plasma LH but only a modest increase inEap1mRNA levels, limited to the MBH. These results indicate that hypothalamicEap1expression is not directly controlled by ovarian steroids and suggest thatEap1expression increases at puberty driven by ovary-independent, centrally initiated events. The expression ofEap1, a transcriptional regulator of reproductive function, increases in the hypothalamus at puberty in an ovary-independent manner, suggesting thatEap1contributes to the centrally originated events that initiate puberty. When examined superficially, the process governing the secretory activity of GnRH neurons appears to be simple: variations in GnRH output are determined by synchronized changes in transsynaptic and glial inputs to GnRH neurons. In turn, these changes are influenced by signals of hormonal, metabolic, and circadian nature. The system, however, not only is composed of different subpopulations of neurons and glial cells of diverse chemical phenotypes but also requires a myriad of ligands, receptors, synaptic specifiers, cell-cell adhesion molecules, intracellular signaling complexes, and transcriptional regulators. Needless to say, for this complex machinery to generate a physiologically meaningful switch in GnRH output, Sulfamonomethoxine it requires to function in a Sulfamonomethoxine highly interactive and coordinated fashion. In an initial attempt to address this issue, it has been proposed that this neuroendocrine regulation of reproductive development requires a level of control provided by gene networks that, operating within the neuroendocrine brain, coordinate neuronal-glial interactions in a developmentally regulated manner (1). Although Rabbit Polyclonal to Chk1 there is no doubt that regulatory control systems such as this one have the potential for thousands of interactions, it is also clear that this heart of such complex systems always consists of a handful of genes encoding transcription factors. Those involved in the central control of reproductive function would be expected to establish the conditions required for the productive engagement of neuron-to-neuron, neuron-to-glia, and glia-to-neuron circuitries controlling GnRH secretion, regardless of the transcriptional process they control. Our knowledge of the number and composition of regulatory gene networks that may run in the hypothalamus to control sexual development is usually rudimentary at best. However, at least one of these presumptive networks and its major hubs has been recognized (2), and evidence has been offered implicating three genes as potential upstream transcriptional regulators of the pubertal process:Oct2(3),Ttf1(4), andEap1(5). The latter is an intronless Sulfamonomethoxine gene, earlier known as chromosome 14 open reading frame 4 (C14ORF4) (6).Eap1encodes a nuclear protein expressed in neurons involved in the stimulatory and inhibitory control of GnRH secretion, including GnRH neurons themselves, as well as glutamatergic, GABAergic, and proenkephalinergic neurons.Eap1also has dual transregulatory activity; it activates the GnRH promoter but represses the preproenkephalin gene, which is usually inhibitory to the pubertal process. Reducing hypothalamicEAP1expressionin vivousing small interfering RNAs delayed puberty and disrupted estrous cyclicity, indicating that enhanced at puberty 1 (EAP1) is necessary for the timely activation of GnRH secretion at puberty and for the periodic fluctuations in GnRH release associated with the estrous cycle (5). Because puberty is initiated by events that occur centrally (7,8,9), a concern that needs to be made when implicating genes in the process that units puberty in motion is whether the pubertal expression of such genes requires the stimulatory effect of gonadal steroids. If it does, one may not presume that the gene in question is usually abona fidecomponent of theprimum movensof puberty, even if the gene is still important (or even crucial) for puberty to take place.Ttf1andOct2may be early components of the initiating process, because their expression raises before puberty without the need.