Periovulatory Expression of Hydrogen Peroxide-Induced Sulfiredoxin and Peroxiredoxin 2 in the Rat Ovary: Gonadotropin Regulation and Potential Modification

Abstract

Reactive oxygen species are involved in ovulation. The aim of this study was to examine gonadotropin regulation of antioxidant enzyme sulfiredoxin (Srx) and peroxiredoxin 2 (PRDX2) expressions and modification during the ovulatory process in rats. Administration of antioxidants in vivo reduced ovulation rate and cumulus expansion. LH treatment increased H(2)O(2) levels within 15 min, which, in turn, induced Srx gene expression in cultured preovulatory follicles. Treatment of preovulatory follicles with catalase suppressed the stimulatory effect of LH on Akt phosphorylation. LH- or H(2)O(2)-stimulated Srx mRNA levels were suppressed by inhibitors of antioxidant agents and MAPK kinase. An in vivo injection of equine chorionic gonadotropin-human chorionic gonadotropin (hCG) stimulated Srx mRNA within 1 h in granulosa but not thecal cells of preovulatory follicles. Srx protein levels were stimulated from 3 h post-hCG injection. Immunofluorescence analysis revealed that oocytes expressed the Srx protein. Furthermore, hCG treatment increased Srx expression in mural granulosa, theca and cumulus cells, but the Srx protein was not detected in corpora lutea. Gene expression of PRDX2, identified as an Srx-dependent modified enzyme, was stimulated by gonadotropins. In situ hybridization analysis demonstrated that PRDX2 mRNA was detected in oocytes and theca cells as well as granulosa cells of some antral and preovulatory follicles. High levels of PRDX2 mRNA were detected in corpora lutea. Total levels of PRDX2 protein were not changed by gonadotropins. However, levels of hyperoxidized PRDX2 increased within 2-3 h after the hCG injection. Taken together, gonadotropin stimulation of Srx expression and PRDX2 modification in the ovary suggest the existence of an antioxidant system to maintain H(2)O(2) production and elimination during the periovulatory period.

Role of sulfiredoxin in systemic diseases influenced by oxidative stress

“…The effects of antioxidants such as sulforaphane [29], curcumin [29], roasted coffee extracts [30] and 3H-1,2-dithiole-3-thione (D3T) [7] have been studied with respect to sulfiredoxin. They induced a significantly higher expression of this antioxidant, whereas agents such as rutin [31], tiron [32] and diphenylene iodonium chloride [32] show a significant decrease in its expression. Further studies can be done to probe into the exact mechanism of action of these agents on sulfiredoxin.…”

The Ovarian Antral Follicle: Living on the Edge of Hypoxia or Not?1

“…LH induction of ovulation in rats is accompanied by an increase in reactive oxygen species (ROS) generation that facilitates epidermal growth factor receptor (EGFR) and downstream signaling events [55]. At the same time, intracellular antioxidant mechanisms increase in response to this activity [56]. Interestingly, Yalu et al [35] found that H 2 O 2 treatment of bovine granulosa cells stabilized HIF1A protein.…”

Cumulus Cell-Expressed Type I Interferons Induce Cumulus Expansion in Mice1

“…The COCs were collected separately from the granulosa cells by pipette in a complete αMEM (supplemented with 25 mM HEPES, 0.25 mM sodium pyruvate, 3 mM Lglutamine, 100 U/ml penicillin and 100 µg/ml streptomycin) and treated as described previously [18].…”

“…Immunofluorescent analyses was performed as previously described [18] with primary antiIfnα, anti-Ifnβ or anti-phospho Ifnar1 antibodies (1:50) and secondary antibodies tagged with AlexaFluor-488 (1:100; Invitrogen, Carlsbad, CA). Digital images were captured using a TCS SP5 AOBS laser-scanning confocal microscope (Leica Microsystems, Heidelberg, Germany) with a 20× objective located at Korea Basic Science Institute (Gwangju, Korea).…”

“…Lysates of COCs (5 µg) were resolved by 6-16% gradient SDS-PAGE and transferred to nitrocellulose membranes (Amersharm Bioscience, Arlington Heights, IL) as previously described [18]. The transferred membrane was blocked with 3% skim milk before immunoblotting using a primary antibody (1:500 final dilution) and a horseradish peroxidaseconjugated secondary IgG (1:1,000 final dilution).…”