The nucleus is an organelle that must grow and restructure in each cell cycle. Tight control of nuclear shape and size is essential for proper cell function, and aberrant regulation of interphase nuclear morphology has been implicated in aging and disease. In mitosis, remodelling of the double-membrane nuclear envelope (NE) allows chromosome segregation and formation of the daughter nuclei. The outer nuclear membrane is continuous with the endoplasmic reticulum (ER). Organization, growth and remodelling of the NE must be considered in the context of this intimate relationship with the ER. Yet, we do not understand how membrane is allocated to enable NE growth, or how the boundaries between the NE and the ER are established and maintained. Building on our work identifying exquisite cell cycle-dependent regulation of nuclear membrane expansion, this project will tackle these fundamental questions using molecular genetics, imaging, and synthetic biology approaches in fission yeast and mammalian cells.
Objectives:
1. Y1. Developing genetically encoded tools, e.g., orthogonal light-, chemical-, or autonomous cell-cycle-controlled systems manipulating membrane biosynthesis with fine spatiotemporal resolution (molecular genetics, optogenetics, protein design).
2. Y2. Using these tools to probe the roles of chromatin-interacting inner nuclear membrane proteins and membrane shaping and remodelling complexes (e.g., ESCRT-III/Vps4) in membrane allocation to the nucleus and maintenance of the NE-ER boundary (molecular genetics, advanced microscopy, CRISPR).
3. Y3-Y4. Pursuing interesting leads further through appropriate experimental approaches including ultrastructural analyses and biochemistry, to reveal the mechanistic basis of these functional interactions (molecular biology, genetics, lipid and protein biochemistry, electron microscopy).