High-fat diet-induced and genetically inherited obesity differentially alters DNA methylation profile in the germline of adult male rats

Abstract

Background 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. Results 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. Conclusion 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.

Restoring Impaired Fertility Through Diet: Observations of Switching From High-Fat Diet During Puberty to Normal Diet in Adulthood Among Obese Male Mice

“…In our present study, paternal obesity has been associated with low average litter weight. Previous study has demonstrated that paternal obesity induced by high-fat diet can affect offspring metabolic by means of epigenetic mechanisms ( 58 ). A recent work demonstrated paternal exposure to type 2 diabetes mediates intergenerational and transgenerational effects on the reproductive health of the offspring, especially on sperm quality ( 59 ).…”

Parental High-Fat High-Sugar Diet Intake Programming Inflammatory and Oxidative Parameters of Reproductive Health in Male Offspring

“…Evidence suggest that high-fat diet intake could alter the DNA methylation profile in the germline of adult male rats and that could partially transmit the altered epigenetic signatures of developmental importance via sperm to the embryo causing embryo loss ( Deshpande et al, 2020 ). It is known that high-fat diet intake increases adiposity in the individual per se and several studies focusing on reproductive health have shown that either maternal or paternal high-fat diet intake is able to program increased adiposity in male offspring, besides increasing adiposity in the progenitors ( Palmer et al, 2012 ; Fullston et al, 2013 ; Fan et al, 2018 ; Deshpande et al, 2020 ; Sertorio et al, 2021 ).…”

“…Evidence suggest that high-fat diet intake could alter the DNA methylation profile in the germline of adult male rats and that could partially transmit the altered epigenetic signatures of developmental importance via sperm to the embryo causing embryo loss ( Deshpande et al, 2020 ). It is known that high-fat diet intake increases adiposity in the individual per se and several studies focusing on reproductive health have shown that either maternal or paternal high-fat diet intake is able to program increased adiposity in male offspring, besides increasing adiposity in the progenitors ( Palmer et al, 2012 ; Fullston et al, 2013 ; Fan et al, 2018 ; Deshpande et al, 2020 ; Sertorio et al, 2021 ). Our model showed that high-fat and high-sugar diet intake increased the adipose tissue weight in both progenitors and that there was an interaction effect of maternal and paternal diet intake increased adiposity of retroperitoneal and epididymal adipose tissue in adult male offspring, evidencing the synergistic effect of the paternal and maternal diets combined.…”

“…Adipose tissue accumulation high-fat diet-induced can be related to altered DNA methylation profile in the germline of adult male rats, such as altered expression pattern of DNA methyltransferases (DNMTs) in the testis ( Deshpande et al, 2020 ). It can also be related to the development of an inflammatory state in the male genital tract, with the production of the cytokines tumor necrosis factor alpha (TNF-α), interleukin 6 (IL-6), interleukin 1β (IL-1β), and interleukin 10 (IL-10) ( Tremellen, 2016 ; Fan et al, 2018 ; Yi et al, 2020 ).…”

Transgenerational Transmission of Epigenetic Modifications in Development of Obesity and Other Chronic Diseases

“…High-fat diet reduces global genomic DNA methylation levels in the sperm and in the spermatozoa of the offspring [26,27]. Increased H3K9 acetylation associated with decreased sirtuin 6 (SIRT6) deacetylases in the nucleus of male mouse sperm caused by high-fat diet is associated with increased DNA damage [28].…”