Human Chorionic Gonadotropin-Dependent Upregulation of Genes Responsible for Estrogen Sulfoconjugation and Export in Granulosa Cells of Luteinizing Preovulatory Follicles. Brown KA et al. Estrogen sulfotransferase (EST) is responsible for the sulfoconjugation of estrogens, thereby changing their physical properties and preventing their action via the estrogen receptors. These sulfoconjugated steroids no longer diffuse freely across the lipid bilayer, instead, they are exported by members of the ATP-binding cassette family, like ABCC1. The objective of this study was to investigate the regulation of EST and ABCC1 during human chorionic gonadotropin (hCG)-induced ovulation/luteinization. The transcripts for EST and ABCC1 were cloned by RT-PCR and the regulation of their mRNAs was studied in preovulatory follicles obtained during estrus at 0, 12, 24, 30, 33, 36 and 39 h after hCG. Results obtained from RT-PCR/Southern blot analyses showed significant changes in steady-state levels of both EST and ABCC1 mRNA after hCG treatment (P < 0.05). In granulosa cells, a significant increase in EST transcript was observed 30-39 h post-hCG. Similarly, ABCC1 transcript levels were induced in granulosa cells 12-39 h post-hCG. In contrast, no significant changes in either EST or ABCC1 were detected in theca interna samples after hCG. The increase in EST and ABCC1 transcripts observed in granulosa cells was reflected in preparations of intact follicle walls, suggesting that the granulosa cell layer contributes the majority of EST and ABCC1 expression in preovulatory follicles. The present study demonstrates that follicular luteinization is not only accompanied by a decrease in 17beta-estradiol biosynthesis, but also with an increase in expression of genes responsible for estrogen inactivation and elimination from granulosa cells, such as EST and ABCC1, respectively.
Ovarian localization
Granulosa, Theca
Comment
TISSUE DISTRIBUTION AND HEPATIC AND RENAL ONTOGENY OF THE MULTIDRUG RESISTANCE-ASSOCIATED PROTEIN (MRP) FAMILY IN MICE Maher JM, et al .
Analysis of the mouse genome has revealed eight Multidrug resistance-associated (Mrp) transporters, with mouse homologues for all human MRPs except MRP8. Whereas MRP expression in tissues of humans and rats has been examined, no characterization exists for mice. Furthermore, the ontogeny of mouse Mrps is unknown, and such knowledge may be helpful in understanding age-related pharmacokinetics. Therefore, the purpose of this study was to quantitatively determine: 1) expression of the Mrp family in 12 different tissues, 2) gender variations in Mrp expression in liver and kidney, and 3) whether Mrp expression is altered during development. Highest expression of the Mrp family members is as follows: Mrp1 in testes, ovary, and placenta.