As the second author, I was primarily responsible for the animal experiments. I demonstrated that enforced mitophagy mediated by OMM-PINK1 and PRKN functions effectively in mouse zygotes, and that it slows down the developmental pace of pre-implantation embryos. However, it remains unclear whether this effect is a direct consequence of mitochondrial reduction (as evidenced by a 30–40% decrease in mtDNA levels), or whether it is due to cellular stress associated with enforced mitophagy. To more precisely evaluate the impact of mitochondrial abundance modulation during pre-implantation development, it would be ideal to reduce mitochondrial content at the oocyte stage—an area for future investigation.
Furthermore, we transferred zygotes subjected to enforced mitophagy into surrogate oviducts to assess effects on post-implantation development. We observed no significant differences compared to controls in implantation rates, embryo size, or litter size. Interestingly, mitochondrial levels remained low until E8.5 but recovered to control levels by E12.5. This observation supports previous speculation that mitochondrial amplification does not occur in embryonic tissues between E7.5 and E9.5 and provides experimental evidence for that hypothesis. The recovery of mitochondrial levels by E12.5 also highlights the robustness of embryonic development.
This approach offers a potential platform for manipulating mitochondrial abundance in vivo and may have broad applications in developmental and mitochondrial biology.
(Abstract) Mitochondrial abundance and genome are crucial for cellular function, with disruptions often associated with disease. However, methods to modulate these parameters for direct functional dissection remain limited. Here, we eliminate mitochondria from pluripotent stem cells (PSCs) by enforced mitophagy and show that PSCs survived for several days in culture without mitochondria. We then leverage enforced mitophagy to generate interspecies PSC fusions that harbor either human or non-human hominid (NHH) mitochondrial DNA (mtDNA). Comparative analyses indicate that human and NHH mtDNA are largely interchangeable in supporting pluripotency in these PSC fusions. However, species divergence between nuclear and mtDNA leads to subtle species-specific transcriptional and metabolic variations. By developing a transgenic enforced mitophagy approach, we further show that reducing mitochondrial abundance leads to delayed development in pre-implantation mouse embryos. Our study opens avenues for investigating the roles of mitochondria in development, disease, and interspecies biology.
Schmitz DA, Oura S, Li L, Ding Y, Dahiya R, Ballard E, Pinzon-Arteaga C, Sakurai M, Okamura D, Yu L, Ly P, Wu J. Unraveling mitochondrial influence on mammalian pluripotency via enforced mitophagy. Cell. 2025 Jun 5:S0092-8674(25)00570-7. doi: 10.1016/j.cell.2025.05.020. Epub ahead of print. PMID: 40499542.