Dnmt2-null sperm block maternal transmission of a paramutant phenotype.

Previous studies have shown that Dnmt2-null sperm block the paternal transmission (through sperm) of certain acquired traits, e.g., high fat diet-induced metabolic disorders or white tails due to a Kit paramutation. Here, we report that DNMT2 is also required for the transmission of a Kit paramutant phenotype (white tail tip) through the female germline (i.e., oocytes). Specifically, ablation of Dnmt2 led to aberrant profiles of tRNA-derived small RNAs (tsRNAs) and other small noncoding RNAs (sncRNAs) in sperm, which correlate with altered mRNA transcriptomes in pronuclear zygotes derived from wild type oocytes carrying the Kit paramutation and a complete blockage of transmission of the paramutant phenotype through oocytes. Together, the present study suggests that both paternal and maternal transmission of epigenetic phenotypes requires intact DNMT2 functions in the male germline.