Khdc3 Regulates Metabolism Across Generations in a DNA-Independent Manner [WTMM, WTPP, HFP liver RNA-seq]

Genetic variants can alter the profile of heritable molecules such as small RNAs in sperm and oocytes, and in this manner ancestral genetic variants can have a significant effect on offspring phenotypes even if they are not themselves inherited. Here we show that wild type female mice descended from ancestors with a mutation in the mammalian germ cell gene Khdc3 have hepatic metabolic defects that persist over multiple generations. We find that genetically wild type females descended from Khdc3 mutants have transcriptional dysregulation of critical hepatic metabolic genes, which persist over multiple generations and pass through both female and male lineages. This was associated with dysregulation of hepatically-metabolized molecules in the blood of these wild type mice with mutational ancestry. The oocytes of Khdc3­-null females, as well as their wild type descendants, had dysregulation of multiple small RNAs, suggesting that these epigenetic changes in the gametes transmit the phenotype between generations. Our results demonstrate that ancestral mutation in Khdc3 can produce transgenerational inherited phenotypes, potentially indefinitely. Comparison of hepatic transcriptomes in genetically wild type female mice descended from either Khdc3-null maternal and paternal grandmothers (WT**(M)) or Khdc3-null maternal and paternal grandfathers (WT**(P)) with wild type female mice with all wild type ancestors (WT).

遗传变异（genetic variants）可改变精子与卵母细胞内小分子RNA（small RNAs）等可遗传分子的表达谱。即便此类祖先遗传变异未直接传递给后代，仍可对后代表型产生显著影响。本研究显示，源自携带哺乳动物生殖细胞基因Khdc3突变的祖先的野生型雌性小鼠，存在可跨多代维持的肝脏代谢缺陷。研究发现，源自Khdc3突变体祖先、自身基因型为野生型的雌性小鼠，其肝脏代谢关键基因存在转录失调（transcriptional dysregulation），该失调可跨多代维持，并可通过雌性与雄性谱系传递。该现象与携带突变祖先的野生型小鼠血液中经肝脏代谢的分子失调相关。Khdc3敲除（Khdc3-null）雌性小鼠的卵母细胞，及其野生型后代，均存在多种小分子RNA的表达失调，这表明配子（gametes）中的表观遗传变化（epigenetic changes）可实现表型的跨代传递。本研究结果证实，Khdc3的祖先突变可产生跨代遗传表型（transgenerational inherited phenotypes），且该效应可能持续无限多代。本研究对三类遗传背景为野生型的雌性小鼠的肝脏转录组（hepatic transcriptomes）开展了比较分析：分别为携带Khdc3敲除母系祖父母（外祖母与外祖父）的野生型雌性小鼠（WT**(M)）、携带Khdc3敲除父系祖父母（祖母与祖父）的野生型雌性小鼠（WT**(P)），以及所有祖先均为野生型的野生型雌性小鼠（WT）。