Three mammalian 'Notch'
homologs have been identified. All 3 are very highly conserved relative to the Drosophila gene, which suggests that
they are important for cell differentiation in mammals. 'Delta' and 'Jagged' are Notch ligands .
General function
Ligand
Comment
Cellular localization
Plasma membrane
Comment
Ovarian function
Follicle endowment, Follicle development
Comment
Expression regulated by
Steroids, p4
Comment
P4 down-regulates Jagged2 and Notch1 expression during primordial folliculogenesis. Guo M et al. Nest breakdown and primordial folliculogenesis of the mouse ovary can be inhibited by progesterone (P4) and Notch signaling inhibitors. However, the relationship between these two signals during this process remains unknown. In the present study, transcript levels of Jagged2, Notch1, and their target, Hey2, increased markedly in ovaries during the beginning stage of folliculogenesis (17.5 days post coitus (dpc) to birth). Maternal P4 levels decreased simultaneously. We found that maternal midpregnancy P4 levels significantly inhibited Jagged2, Notch1, and Hey2 expression, and follicle formation in vitro. Maintaining high maternal P4 levels by daily injection also significantly suppressed the expression of Jagged2, Notch1, and Hey2, and follicle formation during late pregnancy. Based on immunohistochemistry, Jagged2 was localized in oocytes and Notch1 was strongly stained in pre-granulosa cells in 19.5 dpc ovaries. Suppression of their function by antibody addition and RNAi markedly inhibited nest breakdown and follicle formation. Taken together, these results demonstrate that maternal P4 levels during midpregnancy can inhibit the expression of Jagged2 and Notch1, which are involved in primordial folliculogenesis, in the mouse fetal ovary.
Ovarian localization
Oocyte, Granulosa
Comment
Johnson J,et al reported that Notch pathway genes are expressed in mammalian ovarian
follicles.
Genes that regulate the proliferation and differentiation of
granulosa cells are beginning to be elucidated. In this study, the expression
patterns of Notch receptor genes and their ligands, which have been shown to
regulate cell-fate decisions in many systems during development, were examined
in the mammalian ovary. In situ hybridization data showed that Notch2, Notch3,
and Jagged2 were expressed in an overlapping pattern in the granulosa cells of
developing follicles. Jagged1 was expressed in oocytes exclusively. Downstream
target genes of Notch also were expressed in granulosa cells. These data
implicate the Notch signaling pathway in the regulation of mammalian
folliculogenesis.
Follicle stages
Antral
Comment
Phenotypes
Mutations
1 mutations
Species: mouse
Mutation name: None
type: null mutation fertility: embryonic lethal Comment:Jiang et al. (1998) examined the in vivo role of the Jag2 gene by making a targeted mutation that removed a domain of
the Jagged-2 protein required for receptor interaction. Mice homozygous for this deletion died perinatally because of
defects in craniofacial morphogenesis. The mutant homozygotes exhibited cleft palate and fusion of the tongue with the
palatal shelves.