Background: Paternal diet reprograms offspring development, placentation and metabolic health, through information carried by sperm. Prior work showed that acute paternal high-fat diet (HFD) remodels sperm small non-coding RNAs (sncRNAs), specifically mitochondria tRNAs, during epididymal maturation, altering early embryonic transcription and offspring metabolism.1 HFD-induced mitochondrial dysfunction was proposed to drive the generation of these RNAs, therefore we sought to examine this mechanism at the proteomic levels and traced its intergenerational consequences.
Methods: 6wk old male mice were fed HFD or low-fat diet (LFD) for two weeks (n = 4 / group), spanning epididymal transit. Immature (caput) and mature (cauda) sperm were profiled by quantitative proteomics. Twenty knockout mouse lines targeting HFD-responsive candidates were screened for fertilisation potential (motility, IVF cleavage/blastocyst rates, pregnancy rate). The mitochondrial DNA repair candidate Wrnip1 knockout mice underwent sperm small RNA sequencing, single-embryo RNA sequencing, and phenotyping across >550 parameters (German Mouse Clinic pipeline). Father-offspring associations are being explored in the LIFE Child human cohort.
Results: HFD remodelled the sperm proteome throughout epididymal maturation, altering 149 proteins in caput sperm, 453 in cauda sperm, and 597 along epididymal transit. Enriched pathways governed zona pellucida binding, motility, oxidative stress and, most strikingly, mitochondrial dysfunction strongly predicted as activated during transit. Mitochondrial RNA polymerase POLRMT (FC = 1.56) and adenine nucleotide translocase lysine methyltransferase ANTKMT (FC = 4.92) were increased in caput sperm. Of the 20 knockout candidates screened, several displayed reduce motility and impaired fertilisation in most, but the lead candidate, Wrnip1 KO recapitulated key features of the dietary response, including shifts in sperm mitochondrial tRNAs and microRNAs. Resulting embryos exhibited altered metabolic transcriptional programmes and delayed developmental trajectories. Adult offspring phenotypes extended beyond HFD-like hypermetabolism to encompass neurobehavioural alterations and anxiety-related traits.
Conclusion: These findings identify mitochondrial homeostasis during epididymal maturation as a mechanistic link between paternal diet and offspring health. Convergent sperm sncRNA signatures point to a common mitochondrial stress signal transmitted at fertilisation, yet the breadth of offspring outcomes challenges a simple one-exposure, onephenotype model and reveals greater complexity in paternal intergenerational inheritance than currently appreciated. Our ShinySpermPlacenta2 and ShinyFatSperm3 apps navigate this complexity by making public paternal epigenetic datasets accessible and linking them to pathophysiologically relevant phenotypes