Regulatory roles of a novel gonadotropin-inducible transcription factor (GIOT) for ovarian functions

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In this study we have tried to identify ovarian target genes for GIOT (Gonadotropin Inducible Ovarian Transcription factor) in order to clarify roles of GIOT in ovarian functions. GIOT seems to bind upstream regulatory regions of target genes for GIOT, and we have already cloned various ovarian genes that are strongly induced by gonadotropin treatment, such as SR-BI (Scavenger Receptor class B type I), NGF-IA (egr-1), StAR (Steroidogenic Acute Regulatory protein), LH-receptor, 20-beta HSD, 3-beta HDS, P450scc, etc. We have checked effects of GIOT on the transcription of these genes. By using luciferase assay system, effects of GIOT on the transcriptional activity of these gonadotropin inducible genes. In addition, we have tried to identify GIOT interacting proteins in rat granulosa cells. As a result, we have cloned a novel gene that encodes a HMG-box type transcriptional regulator, and we named it GCX-1. GCX-1 is found to be expressed exclusively in reproductive organs. Identification of a novel transcription factor specific to reproductive tissues is a fruitful result of this work.