Researchers have rigorously explored the process of gametogenesis in budding yeast, which includes meiosis and the formation of spores, using advanced live imaging methods. Their study indicated that during sporulation, the exit sites of the endoplasmic reticulum, which are the origins of the secretory pathway, undergo significant changes. This transformation allows cells to effectively transport proteins and membrane lipids, thereby aiding in the creation of new spore membranes.
Sexual reproduction is a widespread reproductive method among various species, involving gametogenesis where new individuals are generated through fertilization, conjugation, or mating. In both plants and animals, germ cells differentiate into eggs and sperm, leading to the formation of gametes. Conversely, budding yeast generates spores within diploid cells. Throughout this cycle, novel membrane structures emerge in the cytosol, encasing meiotic haploid nuclei to create spores. Despite understanding this process, the exact mechanisms that govern the creation of these new membrane structures are still not clear.
To deepen their understanding of this process, scientists at the University of Tsukuba employed live imaging techniques to carefully track meiosis and sporulation in budding yeast, documenting the emergence of new membrane structures within the cells. They found that while the number of endoplasmic reticulum (ER) exit sites and the Golgi apparatus decreased, they reconstructed themselves during sporulation. Additionally, they discovered Gip1, a meiosis-specific subunit of type 1 protein phosphatase, to be a critical factor influencing this regulatory process. In cells lacking Gip1, the secretory pathway was not accurately positioned due to issues in reassembling ER exit sites, leading to abnormal spore plasma membranes. This indicates that cells can effectively transport membrane lipids and create new membranes by reorganizing their membrane traffic during sporulation.
The outcomes of this study carry important implications for human health, as many disorders related to gametogenesis and fertilization are linked to irregularities in intracellular membrane transportation. These results could potentially improve the understanding, diagnosis, and treatment of associated pathological processes.
This research was backed by Grants-in-Aid for Scientific Research from Japan’s Ministry of Education, Culture, Sports, Science, and Technology (MEXT) (grant numbers 21K06145 for Y.S., 20K05782 and 23K05006 for H.T., 18H05275 for A.N., 22K06074 for K.I.).
