title: Glutathione S-transferase class μ regulation of apoptosis signal-regulating kinase 1 protein during VCD-induced ovotoxicity in neonatal rat ovaries.
abstract: 4-Vinylcyclohexene diepoxide (VCD) destroys ovarian primordial and small primary follicles via apoptosis. In mice, VCD exposure induces ovarian mRNA expression of glutathione S-transferase (GST) family members, including isoform mu (Gstm). Extra-ovarian GSTM negatively regulates pro-apoptotic apoptosis signal-regulating kinase 1 (ASK1) through protein complex formation, which dissociates during stress, thereby initiating ASK1-induced apoptosis. The present study investigated the ovarian response of Gstm mRNA and protein to VCD. Induction of Ask1 mRNA at VCD-induced follicle loss onset was determined. Ovarian GSTM:ASK1 protein complex formation was investigated and VCD exposure effects thereon evaluated. Phosphatidylinositol-3 kinase (PI3K) regulation of GSTM protein was also studied. Postnatal day (PND) 4 rat ovaries were cultured in control media ± 1) VCD (30 μM) for 2-8 days; 2) VCD (30 μM) for 2 days, followed by incubation in control media for 4 days (acute VCD exposure); or 3) LY294002 (20 μM) for 6 days. VCD exposure did not alter Gstm mRNA expression, however, GSTM protein increased (P<0.05) after 6 days of both the acute and chronic treatments. Ask1 mRNA increased (0.33-fold; P<0.05) relative to control after 6 days of VCD exposure. Ovarian GSTM:ASK1 protein complex formation was confirmed and, relative to control, the amount of GSTM bound to ASK1 increased 33% (P<0.05) by chronic but with no effect of acute VCD exposure. PI3K inhibition increased (P<0.05) GSTM protein by 40% and 71% on d4 and d6, respectively. These findings support involvement of GSTM in the ovarian response to VCD exposure, through regulation of pro-apoptotic ASK1.
authors.affiliation: Department of Animal Science, Iowa State University, Ames, IA 50011, USA.
authors.forename: Poulomi
authors.initials: P
authors.lastname: Bhattacharya
authors.forename: Jill A
authors.initials: JA
authors.lastname: Madden
authors.forename: Nivedita
authors.initials: N
authors.lastname: Sen
authors.forename: Patricia B
authors.initials: PB
authors.lastname: Hoyer
authors.forename: Aileen F
authors.initials: AF
authors.lastname: Keating
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002478:Cells, Cultured; D053138:Cyclohexenes / Q000633:toxicity*; D005260:Female; D005982:Glutathione Transferase / Q000502:physiology*; D048848:MAP Kinase Kinase Kinase 5 / Q000378:metabolism*; D010053:Ovary / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism*; D051381:Rats; D011916:Rats, Inbred F344; D014753:Vinyl Compounds / Q000633:toxicity*
chemical_list: D053138:Cyclohexenes; D014753:Vinyl Compounds; C012606:4-vinyl-1-cyclohexene dioxide; D005982:Glutathione Transferase; D048848:MAP Kinase Kinase Kinase 5