Paternal obesity has been associated with reduced live birth rates. It could lead to inheritance of metabolic disturbances to the offspring through epigenetic mechanisms. However, obesity is a multifactorial disorder with genetic or environmental causes. Earlier we had demonstrated differential effects of high-fat diet-induced obesity (DIO) and genetically inherited obesity (GIO) on metabolic, hormonal profile, male fertility, and spermatogenesis using two rat models. The present study aimed to understand the effect of DIO and GIO on DNA methylation in male germline, and its subsequent effects on the resorbed (post-implantation embryo loss) and normal embryos. First, we assessed the DNA methylation enzymatic machinery in the testis by Real-Time PCR, followed global DNA methylation levels in spermatozoa and testicular cells by ELISA and flow cytometry, respectively. Further, we performed Methylation Sequencing in spermatozoa for both the groups. Sequencing data in spermatozoa from both the groups were validated using Pyrosequencing. Expression of the differentially methylated genes was assessed in the resorbed and normal embryos sired by the DIO group using Real-Time PCR for functional validation. We noted a significant decrease in Dnmt transcript and global DNA methylation levels in the DIO group and an increase in the GIO group. Sequencing analysis showed 16,966 and 9113 differentially methylated regions in the spermatozoa of the DIO and GIO groups, respectively. Upon pathway analysis, we observed genes enriched in pathways involved in embryo growth and development namely Wnt, Hedgehog, TGF-beta, and Notch in spermatozoa for both the groups, the methylation status of which partially correlated with the gene expression pattern in resorbed and normal embryos sired by the DIO group. Our study reports the mechanism by which diet-induced and genetically inherited obesity causes differential effects on the DNA methylation in the male germline that could be due to a difference in the white adipose tissue accumulation. These differences could either lead to embryo loss or transmit obesity-related traits to the offspring in adult life.

中文翻译：

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高脂饮食引起的肥胖和遗传性肥胖会不同程度地改变成年雄性大鼠种系中的 DNA 甲基化谱

父亲肥胖与活产率降低有关。它可能会通过表观遗传机制将代谢紊乱遗传给后代。然而，肥胖是一种多因素疾病，有遗传或环境原因。早些时候，我们使用两种大鼠模型证明了高脂饮食诱导的肥胖（DIO）和遗传性肥胖（GIO）对代谢、激素分布、男性生育力和精子发生的不同影响。本研究旨在了解 DIO 和 GIO 对雄性种系 DNA 甲基化的影响，及其对吸收（植入后胚胎丢失）和正常胚胎的后续影响。首先，我们通过实时 PCR 评估了睾丸中的 DNA 甲基化酶机制，然后分别通过 ELISA 和流式细胞术跟踪了精子和睾丸细胞中的整体 DNA 甲基化水平。此外，我们对两组精子进行了甲基化测序。使用焦磷酸测序验证了两组精子的测序数据。使用实时 PCR 评估 DIO 组培育的再吸收胚胎和正常胚胎中差异甲基化基因的表达，以进行功能验证。我们注意到 DIO 组中 Dnmt 转录本和整体 DNA 甲基化水平显着下降，而 GIO 组则有所增加。测序分析显示，DIO 组和 GIO 组的精子中分别有 16,966 个和 9113 个差异甲基化区域。通过通路分析，我们观察到两组精子中富含参与胚胎生长和发育的通路的基因，即Wnt、Hedgehog、TGF-β和Notch，其甲基化状态与吸收和正常的基因表达模式部分相关。由 DIO 组培育的胚胎。我们的研究报告了饮食诱发和遗传性肥胖对男性种系 DNA 甲基化产生不同影响的机制，这可能是由于白色脂肪组织积累的差异所致。这些差异可能导致胚胎丢失或将肥胖相关特征遗传给成年后代。