PARENT SESSION
Gene Regulation & Function

THE OSP-1 PROMOTER DIRECTS EXPRESSION OF LACZ TO THE OVARIES OF TRANSGENIC MICE.

Garson, Kenneth¹, Dubé, Manon ¹, Connolly, Denise², Hamilton, Thomas², Vanderhyden, Barbara¹, ^{1 2}

ABSTRACT- Our longterm goal is to develop a mouse model of ovarian cancer. Given that the majority of ovarian tumors are believed to arise from the surface epithelium of the ovary, we intend to both express oncogenes and inactivate tumor suppressors specifically in this particular tissue. A prerequisite for the development of this model is the identification of a promoter which is able to drive the transcription of oncogenes specifically in the mouse ovarian surface epithelium (MOSE). Previously, a rat promoter was identified which was active only in the rat ovary and in ovarian tumor cell lines. In order to determine whether this rat ovarian specific promoter (OSP-1) would faithfully direct expression to the mouse ovary, we constructed transgenic mice expressing the lacZ gene under the transcriptional control of the OSP-1 promoter (OSP-lacZ). First, we determined whether the OSP-1 promoter activity was confined to the ovary as had been observed for rat. Expression of the lacZ reporter in mouse organs was determined by Northern blot analysis and by the biochemical detection of lacZ expression with X-gal staining. Using these two methods, we concluded that expression from the OSP-1 promoter is restricted to the mouse ovary. We subsequently identified whether the OSP-1 promoter was active in MOSE. Briefly, MOSE were cultured from mouse ovaries and stained with X-gal. MOSE from OSP-1 transgenic mice expressed lacZ indicating that OSP-1 is active in this cell type. In order to determine whether OSP-1 is active in other cell types of the ovary, the expression of lacZ was determined by immunohistochemical staining of thin sections of the mouse ovary. Expression of lacZ indicated that the OSP-1 promoter is active in granulosa, stromal and epithelial cells of the ovaries of OSP-lacZ transgenic mice. Finally, we have found that the expression of genes from the OSP-1 promoter can be further elevated by using tandem repeats of the OSP-1 promoter. In conclusion, we have determined that the OSP-1 promoter is able to specifically direct gene expression to the mouse ovary in cell types which include the surface epithelium. Multimerized versions of this promoter will be useful for the targeted expression of oncogenes to the mouse ovarian surface epithelium thus facilitating the development of a mouse model of ovarian cancer.

KEY WORDS: mouse, model, ovary, cancer