Paternal eNOS Deficiency Affects Glucose Homeostasis and Liver Glycogen Content in Male Offspring Without Inheritance of eNOS Deficiency Itself

Background: It was shown that maternal eNOS deficiency causes fatty liver disease and numerically lower fasting glucose in female wild-type offspring suggesting that parental genetic variants may influence the offspring's phenotype via epigenetic modifications in the offspring despite the absence of a primary genetic defect. This, however, was not shown so far for paternal genes. Methods; Heterozygous male eNOS knockout mice or wild-type male mice were bred with female wild type mice. The phenotype of wild-type offspring of heterozygous male eNOS knockout mice was compared to offspring from wild type parents. Findings: Global sperm DNA methylation decreased and sperm miRNAs pattern altered substantially. Fasting glucose and liver glycogen storage were increased when analyzing wild type male and female offspring of +/- eNOS fathers. The endocrine pancreas in wild-type offspring was not affected. Wild-type male but not female offspring of +/- eNOS fathers had increased fasting insulin and increased insulin after glucose load. Analyzing candidate genes for liver fat- and carbohydrate metabolism revealed that the glucocorticoid receptor (GR) and peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1a) genes were increased while DNA methylation of GR exon 1A and PGC1a promoter were decreased in the liver of male wild-type offspring of +/- eNOS fathers.   Interpretation: Our study suggests that paternal genetic defects may alter the epigenome of the sperm without transmission of the defect itself and alter in later life of the offspring epigenetically gene expression and hence the phenotype without inheriting the defect itself and these alterations might be offspring sex dependent. Funding Information: This study was financially supported by the “Deutsche Forschungsgemeinschaft” to Dr. Berthold Hocher. Declaration of Interests: The authors have no conflict of interest to disclose Ethics Approval Statement: Study design and experimental protocols were conducted according to the local institutional guidelines for the care and use of laboratory animals and approved by the animal welfare ethical committee of the state of Berlin.