Mitochondrial signals mediate paternal effects on offspring metabolism (RNA-Seq)

Spermatozoa deliver a complex and environment sensitive pool of small non-coding RNAs (sncRNA) to the oocyte at fertilisation, which influences offspring development and adult phenotypic trajectories. Whether mature spermatozoa in the epididymis can directly sense the environment is still not fully understood. Here, we used two distinct paradigms of preconception acute High Fat Diet challenge to dissect epididymal vs spermatogenic contributions to the sperm sncRNA pool and offspring health. We show that epididymal spermatozoa, but not developing germ cells, are sensitive to the environment and identify mitochondrial tRNA fragments as sperm-born sensors. In human spermatozoa, we found mt-tsRNAs in linear association with BMI and showed that paternal overweight at conception is sufficient to double offspring obesity risk and compromise metabolic health. Using mouse genetics and metabolic phenotypic data, we show that alterations of mt-tsRNAs are downstream of mitochondrial dysfunction in mice. Most importantly, single embryo transcriptomics of genetically hybrid two-cell embryos demonstrated sperm-to-oocyte transfer of mt-tsRNAs at fertilisation and implied them in the control of early embryo metabolism. Our study supports the importance of paternal health at conception for offspring metabolism, propose mt-tsRNAs as sperm-born environmental effectors of paternal inheritance and demonstrate, for the first time in a physiological and unperturbed setting, father-to-offspring transfer of sperm mt-tsRNAs at fertilisation. Study to understand transcriptional changes in germ cells and somatic tissues in male mice exposed to preconceptional High Fat Diet (HFD) and Low Fat Diet (LFD) for 2 weeks and their offspring.精子在受精过程中会向卵母细胞递送一组复杂且对环境敏感的小非编码RNA（small non-coding RNAs, sncRNA）库，该RNA库可影响子代发育与成年表型轨迹。目前学界尚未完全明确附睾内的成熟精子能否直接感知外界环境变化。本研究采用两种不同的孕前急性高脂饮食干预模型，以剖析附睾与生精过程对精子sncRNA库及子代健康的贡献。 研究结果显示，附睾精子而非发育中的生殖细胞对环境敏感，并鉴定出线粒体tRNA片段（mitochondrial tRNA fragments）作为精子源性感应分子。在人类精子中，我们发现线粒体tRNA衍生小RNA（mt-tsRNAs）与身体质量指数（BMI）呈线性相关，且证实受孕时父亲超重足以使子代肥胖风险翻倍，并损害子代代谢健康。 借助小鼠遗传学手段与代谢表型数据，我们证明小鼠体内mt-tsRNAs的改变源于线粒体功能障碍。最为关键的是，对遗传杂交二细胞胚胎的单胚胎转录组学（single embryo transcriptomics）分析显示，受精过程中存在精子向卵母细胞的mt-tsRNAs传递，并提示这些片段参与调控早期胚胎代谢。 本研究证实了受孕时父亲健康状态对子代代谢的重要性，提出mt-tsRNAs可作为父系遗传的精子源性环境效应分子，并首次在生理未受干扰的实验条件下，证明了受精过程中精子mt-tsRNAs向子代的父系传递。本研究旨在探究暴露于2周孕前高脂饮食（HFD）与低脂饮食（LFD）的雄性小鼠生殖细胞及体细胞组织的转录变化，及其子代的相关表型。