Treatment of porcine ovarian follicles with tert-butyl hydroperoxide as an ovarian senescence model in vitro.

Ovarian aging is the main reason of female reproductive problems. Excessive oxidative stress can induce ovarian senescence and follicular atresia, thereby reducing the reproductive performance. Follicles were divided into five groups for in vitro culture based on the duration of stimulation with tert-butyl hydroperoxide (t-BHP)-control group and groups 1 h, 2 h, 6 h, and 12 h. The results revealed that the ratio of progesterone (P4) to estradiol (E2) was increased after 24 and 36 h of follicle culture, shifting follicles toward atresia (P < 0.05). Stimulated by 200 µM t-BHP, follicles showed progressive aging phenotype. Senescence-associated ß-galactosidase staining (SA-ß-Gal) showed a significant increase in the number of positive cells (P < 0.05). Reactive oxygen species were also significantly upregulated (P < 0.05). t-BHP treatment for 6 h induced significant increases in Caspase 3, P53, and Foxo1 mRNA and protein levels (P < 0.05) and significant decreases in SOD mRNA and protein levels (P < 0.05). Transcriptome sequencing analysis of the follicles showed that the aged and treatment groups were clustered together in hierarchical clustering. Correlation analysis indicated significant changes at the transcriptome level in the treatment groups versus the control group. The common differentially expressed genes in the treatment groups were enriched in three growth-factor signaling pathways associated with cell proliferation and apoptosis (P53, mTOR, and MAPK). In conclusion, induction of follicular senescence by treatment with 200 µM t-BHP for 6 h is an effective in vitro model to simulate ovarian senescence in sows.

Effect of high-fat diet on the lipid profile of ovarian granulosa cells and female reproduction in mice.

Currently, comorbidities of obesity are becoming increasingly frequent. For example, obese women are more susceptible to reproductive diseases; however, the underlying mechanism remains poorly understood. The present study aimed to explore the effect of obesity on female reproduction and discuss changes of the lipid profile in ovarian granulosa cells. Fifty female mice were randomly divided into two groups, one group was fed high-fat diet, the other group was fed standard control diet, food and water freely. After 12 weeks of feeding, the average body weight of the high-fat diet mice (19.027g) was significantly higher than that of the standard control diet mice (36.877g) (P < 0.05). The tissue sections were stained with oil red O, and the online software mage Pro plus 6.0 analyzed the staining results, the lipids in the ovaries and endometria were found to be different between the two groups. Liquid chromatography-electrospray ionization with tandem mass spectrometry (LC-ESI-MS/MS) analysis of ovarian granulosa cells (GCs) was performed, with a total of 228 different lipids being identified, the abundant of 147 were increased and 81 were decreased in the high-fat diet group. Among them, PI (18:1/20:1) was the most different lipid, and high-fat feeding was 85 times higher than standard control group. Among these different lipids, 44% in phospholipid metabolism, 30% in glycerolipid metabolism, and 30% in fat digestion and absorption. The results of this study laid a theoretical foundation of the effects of diet-induced obesity on female reproduction.

Progress on the study of nucleosome reorganization during cellular reprogramming.

Cellular reprogramming is the process during which epigenetic markers of nuclear genome are deleted and remodeled during sperm-egg binding or nuclear transplantation, thereby rendering differentiated cells totipotent. The main cellular reprogramming methods are cell fusion, somatic cell nuclear transplantation, and induced pluripotent stem cells. Nucleosomes are the basic structural and functional units of chromatin, and nucleosome localization has an important role in regulating gene expression and the state of the cell. The occupancy and location of nucleosomes also change dramatically during cellular reprogramming, while the occupancy of nucleosomes around the transcriptional start site also decreases to promote the expression of pluripotency genes. In this review, we summarize the role of nucleosome localization in gene activation and repression, chromatin remodeling, and transcription factor recognition, with the aim of providing an important basis for an in-depth analysis of cellular reprogramming mechanisms.