PARENT SESSION
SLIDE SESSION 11: GENE REGULATION & FUNCTION
Chairs: Michael Pallidino, Jeanne Wison-Rawles, Leslie Skalla (Trainee)
Univ Ottawa-Arts Hall 257
1:30 PM-3:30 PM
241
JAGGED GENE EXPRESSION IS ALTERED IN GDF-9 NULL AND MOTHEATEN MICE.
Wilson-Rawls, Jeanne1, Johnson, Joshua , Papademetriou, Suzanne , Vanderhyden, Barbara , 1
ABSTRACT- The Notch ligand Jagged1 is normally expressed exclusively in growing oocytes from type 3b to type 6 follicles. Whereas Jagged2, a second member of this ligand family, is restricted in expression to the granulosa cells. We wanted to examine the potential role of the oocyte in regulating the expression of these genes differentially. Oocyte derived factors have been shown to influence granulosa cells by stimulating proliferation and inhibiting differentiation, therefore the expression patterns of these genes were examined in gdf-9-/- mutants. GDF-9 is secreted by oocytes and induces the proliferation of granulosa cells. gdf-9 null mice have follicles that arrest at type 3b. In situ hybridization experiments done on GDF-9 null mutant ovaries demonstrated that Jagged1 was expressed not only in the oocytes, but also in the surrounding granulosa cells. There was no change in the expression of Jagged2. This indicated that GDF-9 inhibits the expression of Jagged1 in the surrounding granulosa cells. The motheaten mice have a defect in the SHP-1 phosphatase, which regulates the tyrosine kinase activity of the Kit receptor. Kit is expressed on oocytes and is involved in primordial germ cell proliferation and oocyte growth. Interestingly, in motheaten mice the expression of Jagged1 was lost in oocytes and this gene was now expressed solely in the granulosa cells. However, Jagged2 was expression was unchanged, it was still limited to the granulosa cells. These data indicate a role for SHP-1 in the induction of Jagged1 expression in the oocyte. Further, the granulosa specific expression of Jagged2 is regulated independently of both GDF-9 and SHP-1.
KEY WORDS: Jagged, Kit, GDF-9, folliculogenesis