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General Comment |
Kajitani T, et al 2004 reported the cloning and characterization of GCX-1, a novel HMG-box transcriptional regulator strongly expressed in rat ovarian granulosa cells.
Specific events in the ovary are dependent on gene expression in the tissue. By screening a rat ovarian granulosa cell cDNA library, a cDNA clone encoding a novel transcription factor-like protein containing a high mobility group (HMG)-box, referred to as granulosa cell HMG-box protein-1 (GCX-1), was identified. The expression of GCX-1 is restricted to the hypothalamus, pituitary, testis, uterus, and ovary, but was not detected in the adrenal gland. An in situ hybridization study revealed that the expression of GCX-1 was restricted to granulosa cell layers in early stage follicles, and the expression was very low in large antral follicles and the corpus luteum, but localized expression in the testis or pituitary was not clear. Endogenous GCX-1 protein in the granulosa cells was identified by a Western blot analysis, and an analysis using the green fluorescence protein (GFP)-GCX-1 fusion protein revealed that the GCX-1 protein was localized in the cell nucleus. GAL4 fusion protein-based assays demonstrated that GCX-1 is a potent transcriptional activator, and its putative transactivation domain was mapped to the region between amino acid residues 25 and 63 from the N terminus. These data strongly suggest that GCX-1 is likely a novel transcriptional activator that is exclusively expressed in reproductive tissues involving the hypothalamo-pituitary-gonadal axis, and functions as a specific regulator of follicular development, and may also participate in other specific events related to reproduction, particularly in the female.
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