tsRNAs Mediate Intergenerational Inheritance by Concertedly Suppressing Wnt and PPAR Pathways

The Developmental Origins of Health and Disease hypothesis posits that paternal environmental exposures program offspring metabolic health via sperm epigenetic factors, particularly tRNA-derived small RNAs (tsRNAs). Cadmium (Cd) is a ubiquitous environmental pollutant known to impair reproductive health, but epigenetic links to offspring metabolic disorders are unclear. Using paternal Cd exposure, we elucidate sperm tsRNA pathogenic mechanisms in intergenerational inheritance.

We validated candidate tsRNA functions via zygotic microinjection of agomirs in mice and transfection in AML12 cells in vitro. For mechanistic insights, we conducted blastocyst low-input RNA sequencing, liver transcriptomics, and in vitro assays (luciferase, Western blot, immunofluorescence).

Transfection of Cd-upregulated sperm tsRNAs (tRF-Leu-CAA, tRF-Ala-AGC) inhibited PPAR signaling in AML12 cells and caused lipid disorders. In vivo, microinjection recapitulated paternal Cd effects: impaired embryogenesis and adult metabolic syndromes (weight gain, hyperlipidemia, hepatic steatosis). Mechanistically, tsRNAs suppressed Wnt and PPAR pathways from the two-cell stage, with LEF1/WNT5A as direct Wnt targets; this suppression persisted in adult liver.

We propose a two-hit mechanism: first hit via early embryonic Wnt/PPAR co-suppression, second hit via sustained inhibition into adulthood, driving metabolic dysregulation. Thus, tsRNAs are key epigenetic vectors linking paternal Cd exposure to offspring metabolic health.