Laser Capture Microdissection isolation of preovulatory granulosa cells from WT and bERKO ovaries

Determining the spatial and temporal expression of genes involved in the ovulatory pathway is critical for the understanding of the role of each estrogen receptor in the modulation of folliculogenesis and ovulation. Estrogen receptor (ER) is highly expressed in ovarian granulosa cells and mice lacking ER (ERKO) are subfertile due to inefficient ovulation. Previous work has focused on isolated granulosa cells or cultured follicles and while informative, provides confounding results due to the heterogeneous cell types present including granulosa, theca and oocytes and exposure to in vitro conditions. Herein, we isolated preovulatory granulosa cells from WT and ER-null mice using laser capture microdissection to examine the genomic transcriptional response downstream of PMSG (mimicking FSH) and PMSG/hCG (mimicking LH) stimulation. This allows for a direct comparison of in vivo granulosa cells at the same stage of development from both WT and ER-null ovaries. ER-null granulosa cells showed altered expression of genes known to be regulated by FSH (Akap12 and Runx2) as well as not previously reported (Arnt2 and Pou5f1) in WT granulosa cells. Our analysis also identified 304 genes not previously associated with ER in granulosa cells. LH responsive genes including Abcb1b and Fam110c show reduced expression in ER-null granulosa cells; however novel genes including Rassf2 and Megf10 were also identified as being downstream of LH signaling in granulosa cells. Collectively, our data suggests that granulosa cells from ER-null ovaries may not be appropriately differentiated and are unable to respond properly to gonadotropin stimulation

12

Binder AK, Rodriguez KF, Hamilton KJ, Stockton PS, Reed CE, Korach KS