GATA Factors Are Essential for Activity of the Neuron-Specific Enhancer of the Gonadotropin-Releasing Hormone Gene

Abstract

The multicomponent neuron-specific enhancer of the gonadotropin-releasing hormone (GnRH) gene specifically targets expression to the GnRH-secreting neurons of the hypothalamus, a small population of specialized cells which play a central role in regulating reproductive function. Utilizing the GnRH-secreting hypothalamic neuronal cell line, GT1, as a model system, we show that members of the GATA family of transcription factors regulate GnRH transcription through two GATA factor-binding motifs that occur in a tandem repeat within the GnRH neuron-specific enhancer. Although GT1 cells contain GATA-2 and GATA-4 mRNAs, only GATA-4 was detected in a GnRH enhancer GATA site-specific complex. Cotransfection experiments with wild-type and mutant GnRH enhancer reporter plasmids with wild-type and dominant negative GATA factor expression vectors demonstrated that both GATA-binding elements are functional in the context of the enhancer. We conclude that GATA-binding proteins are important factors in regulating the neuron-specific expression of the GnRH gene in hypothalamic cells. Although the presence of GATA-2 in a neuronal cell type is not unusual, the presence of GATA-4 in GT1 cells is novel for a neuronal cell type. However, the presence of GATA-4 is consistent with the unique developmental origin of GnRH neurons and may provide insight into the transcriptional mechanisms mediating the differentiation of this limited population of GnRH-secreting neurons.