Transposable elements (TEs) promote genetic innovation but also threaten genome stability. Despite multiple layers of host defence, TEs actively shape mammalian-specific developmental processes, particularly during pre-implantation and extra-embryonic development and at the maternal–fetal interface. Here, we review how TEs influence mammalian genomes both directly by providing the raw material for genetic change and indirectly via co-evolving TE-binding Krüppel-associated box zinc finger proteins (KRAB-ZFPs). Throughout mammalian evolution, individual activities of ancient TEs were co-opted to enable invasive placentation that characterizes live-born mammals. By contrast, the widespread activity of evolutionarily young TEs may reflect an ongoing co-evolution that continues to impact mammalian development.

转座因子 (TE) 促进遗传创新，但也威胁基因组稳定性。尽管存在多层宿主防御，但 TE 积极塑造哺乳动物特有的发育过程，特别是在植入前和胚胎外发育期间以及母胎界面。在这里，我们回顾了 TE 如何通过为遗传变化提供原材料直接影响哺乳动物基因组，以及通过共同进化的 TE 结合 Krüppel 相关盒锌指蛋白 (KRAB-ZFP) 间接影响哺乳动物基因组。在整个哺乳动物进化过程中，古代 TE 的个体活动被增选以实现具有活产哺乳动物特征的侵入性胎盘形成。相比之下，进化上年轻的 TE 的广泛活动可能反映了持续影响哺乳动物发育的持续共同进化。