| In recent years,the incidence rate of infertility and pregnancy complications caused by obesity in childbearing age women has been greatly increased.The influence of obesity on human reproductive health has recently gained a lot of attention.Therefore,it is of great significance to research the impact of obesity on female reproductive health and its mechanism for improving the fertility outcomes of patients with obesity and its related metabolic diseases.MOTS-c is encoded by the mitochondrial 12S rRNA short open reading frame(sORF),and involving in the regulation of insulin sensitivity and metabolic homeostasis,which has significant effect on weight loss and metabolic disorder in obese mice.We found that the ovarian reserve of obese mice was seriously damaged,and the fertility decreased significantly.What’s more,in the High-fat-diet-induced obese mice,MOTS-c is down regulated in oocytes and early embryos,which leads to early embryonic arrest and fertility decreased by affecting zygotic genome activation.These results suggest that the abnormal embryonic development of the obesity may be related to the abnormal zygotic genome activation caused by maternal factors.Objective:To explore the effect of obesity on fertility in female mouse model and the role of MOTS-c in early embryonic development and its main mechanism.Methods:In this study,obese female mice model induced by high-fat-diet and leptin gene deficient obese(ob/ob)mice model were used as the researching objects.Transcriptome analysis of gene expression in oocytes and early embryos,morpholino and siRNA interference target gene expression,qPCR,immunofluorescence staining and other experimental methods were used to verify the changes of related gene mRNA and protein expression levels.Research contents:We stablished a high-fat diet-induced obese female mouse model to detect the fertility changes,and collect mouse MII stage oocytes,zygotes and 2-cell embryos for transcriptome sequencing for analyzing the situation of zygotic genome activation.In order to verify the expression changes of typical genes,qPCR and immunofluorescence staining were conducted.MOTS-c in zygote was knocked down by morpholino antisense technology,followed then by observing the embryonic development.Finally,obese mouse models were intraperitoneally injected with MOTS-c to study the relationship between embryonic arrest and the decrease of MOTS-c expression in early embryos.Results:Compared with the normal diet group,the number of ovulation(P=0.0003)and the quality of oocytes are decreased.Accompanying with the increasing of the concentration of reactive oxygen species(P<0.0001),the rate of spindle assembly(P=0.0005)and the chromosome arrangement(P=0.014)are disordered.What’s more,the weight of fetal(P=0.0049)and the litter size are seriously decreased(P=0.0007)respectively.Reduction of the expression of MOTS-c results in impaired peroxisome matrix protein transport in MII stage oocytes and early embryos in obese mouse models.At the same time,knockdown of MOTS-c also affected the peroxisome matrix protein transport.We observed that knockdown of MOTS-c in embryos caused abnormal activation of Acsl4 gene due to abnormal zygotic genome activation as same as what happened in obese mice.A continuous intraperitoneal injection of MOTS-c in obese mice could cause a measurable weight loss(P=0.007),glucose tolerance recovery,litter size and fetal weight increasing.Conclusion:High-fat diet-induced obesity decreased oocyte quality and caused abnormal development of early embryo.Mitochondrial derived small molecular polypeptide MOTS-c affects peroxisome matrix protein transport and regulates fatty acid metabolism.The decrease of MOTS-c expression in oocytes and early embryos of obese mice leads to the disorder of peroxisome matrix protein transport and abnormal fatty acid metabolism,which affects zygotic genome activation and leads to embryo development arrest.MOTS-c improves metabolism,saves ovarian function and improves fertility in high-fat diet-induced obese mice. |
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