Ataxia–telangiectasia mutated coordinates the ovarian DNA repair and atresia-initiating response to phosphoramide mustard

Abstract

Ataxia–telangiectasia-mutated (ATM) protein recognizes and repairs DNA double strand breaks through activation of cell cycle checkpoints and DNA repair proteins. Atm gene mutations increase female reproductive cancer risk. Phosphoramide mustard (PM) induces ovarian DNA damage and destroys primordial follicles, and pharmacological ATM inhibition prevents PM-induced follicular depletion. Wild-type (WT) C57BL/6 or Atm+/− mice were dosed once intraperitoneally with sesame oil (95%) or PM (25 mg/kg) in the proestrus phase of the estrous cycle and ovaries harvested 3 days thereafter. Atm+/− mice spent ~25% more time in diestrus phase than WT. Liquid chromatography with tandem mass spectrometry (LC-MS/MS) on ovarian protein was performed and bioinformatically analyzed. Relative to WT, Atm+/− mice had 64 and 243 proteins increased or decreased in abundance, respectively. In WT mice, PM increased 162 and decreased 20 proteins. In Atm+/− mice, 173 and 37 proteins were increased and decreased, respectively, by PM. Exportin-2 (XPO2) was localized to granulosa cells of all follicle stages and was 7.2-fold greater in Atm+/− than WT mice. Cytoplasmic FMR1-interacting protein 1 was 6.8-fold lower in Atm+/− mice and was located in the surface epithelium with apparent translocation to the ovarian medulla post-PM exposure. PM induced γH2AX, but fewer γH2AX-positive foci were identified in Atm+/− ovaries. Similarly, cleaved caspase-3 was lower in the Atm+/− PM-treated, relative to WT mice. These findings support ATM involvement in ovarian DNA repair and suggest that ATM functions to regulate ovarian atresia.

Obesity partially potentiates dimethylbenz[a]anthracene-exposed ovotoxicity by altering the DNA damage repair response in mice

“…It is known that DDR molecules downstream of ATM are blunted due to DMBA exposure in obese mice, albeit in older mice [ 22 ]. It is also known that both ATM inhibition [ 67 ] and Atm haploinsufficiency [ 24 ] impair depletion of damaged ovarian follicles. Thus, this lack of primary follicle depletion by DMBA could support a defective ovarian DDR response.…”

“…Quantification of the intensity of the BRCA1 stain in oocytes revealed a decrease in BRCA1 in the oocytes of primary follicles in all treatment groups as compared with lean control. Previously our group has reported a decrease in BRCA1 abundance with progressive obesity [ 22 ] and in 10-week-old mice no observable changes in BRCA1 were noted suggesting that the alterations in BRCA1 previously noted could be age-related [ 24 ]. Herein decreased BRCA1 in the oocytes of primary follicles due to both DMBA and obesity exposure was observed.…”

“…Improperly repaired DNA can lead to the loss of genomic integrity, altering cell growth or leading to cell death [ 21 , 22 ]. The ovary is capable of DDR [ 23 ] and responds to DNA double-stranded breaks (DSBs) by activating DDR proteins, including those in the ataxia telangiectasia mutated (ATM) pathway [ 24 ]. Upon sensing DSBs, ATM triggers a cascade of phosphorylation events, leading to cell cycle arrest for DNA repair, and if the damage is beyond repair, the cell undergoes apoptosis [ 25 ].…”

KU60019 induced ATM blockage regulates GPR91/has-miR-576-3p to inhibit ovarian cancer progression

“…Ataxia telangiectasia mutated (ATM) could be activated in response to DNA damage, which lead to phosphorylation of downstream proteins to regulate apoptosis and cell cycle in cancer (12). It was reported that loss of ATM prolonged the diestrus phase in mice, ATM inhibition suppressed phosphoramide mustard induced destroys primordial follicles (13). However, the exact mechanism underlying tumor growth inhibition induced by ATM blockage were still unclear.…”