Modulation of mitochondrial abundance in pluripotent stem cells and embryos

For billions of years, mitochondria have fueled the development of all eukaryotic organisms. Despite their ubiquitous presence, whether mitochondria are necessary for eukaryotic life has never been directly assessed, as strategies to generate eukaryotic models with partially reduced, or completely eliminated, mitochondrial content are limiting. To establish a system in which we can study the necessity for mitochondria in mammalian physiology and development, we established an enforced mitophagy system that allows for the efficient and complete removal of mitochondria from human and mouse pluripotent stem cells (PSCs). We found these cells to maintain many aspects of pluripotency, including the abilities to maintain expression of most mitochondrial genes and give rise to other cell types despite a complete lack of mitochondria. Moreover, we devised a transgenic method that allows for the reduction of mitochondria from in vivo mouse embryos and reveal a threshold of mitochondrial abundance necessary to maintain pre-implantation embryonic development and embryo cleavage. To study how mitochondria influence gene expression in pluripotent stem cells, we established mESCs and hESCs devoid of mitochondria using an inducible PRKN enforced mitophagy system.