Cells must stay in shape in order to successfully reproduce
A team of researchers led by the Francis Crick Institute has found that staying in the right shape is essential for the reproductive success of cells. The study demonstrated that cells must maintain a certain proportion in order to properly divide.
The researchers identified a biological foundation for scaling, by which cells stay proportionate as they shrink or grow. Although this phenomenon continues throughout life, its physiological origins have remained unclear.
The analysis, which was focused on yeast cells from the related S. japonicus and S. pombe species, showed that scaling plays a vital role in cell division. In order to divide, fission yeast cells copy their DNA and then split down the middle to create two new cells.
According to the study, staying in the right shape is essential for cells to find their “middle” where the split should occur. For example, fission yeast cells are usually pill-shaped, and the researchers found that if the cell is too round it cannot receive clear signals about where its middle is located. As a result, two copies of DNA may end up in one cell, with none in the other.
“If a division leaves two copies of DNA in one cell, the one without DNA will die and the one with two copies is likely to have problems when it next divides, which in human cells can lead to cancer,” explained study co-author Professor Snezhka Oliferenko.
“To avoid this, it’s vital that the division happens in the right place. We found that a cell’s shape determines where it will divide, highlighting the crucial function of scaling at the cellular level. This helps to answer the fundamental evolutionary question of why and how organisms would evolve the ability to scale when their size changes.”
In an effort to conserve nutrients, yeast cells that are genetically edited or nutritionally restricted shrink when they divide.
“We found that S. japonicus relies on a gene called rga4 to regulate growth so the cell keeps its shape when it shrinks,” said study lead author Dr. Ying Gu. “The cells simply divided into thinner cells of the same shape, which were able to live and multiply as normal.”
The team discovered that when the rga4 gene was inhibited, the cells lost their ability to scale, grew too wide, and divided off-center. However, when these genetically-edited cells were grown in a narrow channel to keep them thin, they divided normally.
“As long as the length-to-width aspect ratio is correct, S. japonicus can accurately divide in the middle and continue to thrive,” said Professor Snezhka.
“It’s a beautiful organism to study, as it allows us to test fundamental biological principles and get clear, elegant results. We can ask questions like ‘What’s the point in scaling?’, ‘Why does cell shape matter?’ and many more. By studying the similarities and differences between S. japonicus and sister species like S. pombe, we can gain insights into processes that are fundamental to life itself.”
The study is published in the journal Nature Communications.
Image Credit: Snezhka Oliferenko