A systematic genomic screen implicates nucleocytoplasmic transport and membrane growth in nuclear size control.
How cells control the overall size and growth of membrane-bound organelles is an important unanswered question of cell biology. Fission yeast cells maintain a nuclear size proportional to cellular size, resulting in a constant ratio between nuclear and cellular volumes (N/C ratio). We have conducted a genome-wide visual screen of a fission yeast gene deletion collection for viable mutants altered in their N/C ratio, and have found that defects in both nucleocytoplasmic mRNA transport and lipid synthesis alter the N/C ratio. Perturbing nuclear mRNA export results in accumulation of both mRNA and protein within the nucleus, and leads to an increase in the N/C ratio which is dependent on new membrane synthesis. Disruption of lipid synthesis dysregulates nuclear membrane growth and results in an enlarged N/C ratio. We propose that both properly regulated nucleocytoplasmic transport and nuclear membrane growth are central to the control of nuclear growth and size.
Kume K, Cantwell H, Neumann FR, Jones AW, Snijders AP, Nurse P