IFOM – Istituto Fondazione di Oncologia Molecolare, Milan, ITALY

Wednesday, 27 April 2022 | 3:00 pm – ICGEB Trieste, ITALY

Nuclear envelope tension impacts on nuclear volume

Host: G. Del Sal

Nuclear size is a distinct trait of a cell population. While the nuclei of most normal cells tend to be either round or oval, abnormal nuclear shape or size are well-known hallmarks of cancer. Generally, nuclear size is expected to be directly related to cell size and, as the latter, to continuously increase along the cell cycle. In fission yeast it has already been shown that the nucleus-to-cell (N/C) volume ratio remains constant during growth. On the contrary, few results are available in mammalian cells. As well, the mechanisms linking cell and nuclear volume are unclear.

By extending the fluorescence exclusion method (FXM), already employed to quantify total cell volume, we developed a method to measure in living cell and in real time both cytoplasmic and nuclear volumes. We then applied this methodology to normal and transformed cell lines. Surprisingly, our analysis revealed that cell and nuclear volume are growing in time following different laws. Moreover, we found that the tension exerted by the cytoskeleton on the nuclear envelope strongly affects the nuclear volume and consequently the N/C volume ratio.

Our results reveal the contribution of mechanical forces on the regulation of nucleus size.

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