In high school biology, students typically learn about cell division, known as mitosis, as a crucial process for life forms. Traditionally, it has been taught that during mitosis, a parent cell becomes spherical before dividing into two daughter cells of identical size and shape. A new study, however, is set to challenge this foundational concept.
Researchers have discovered that mitosis does not always include cell rounding, meaning that the resulting daughter cells are not always symmetrical or identical in function. Their findings are published in a study in the journal Science and have significant implications for understanding cell division in diseases like cancer.
Shane Herbert, the study’s co-lead author and a researcher at the University of Manchester’s Faculty of Biology, Medicine, and Health, stated, “Students learn that when a cell divides, it will generate a uniform spherical shape. Our study, however, shows that in real living organisms, it is not as simple as that.”
The researchers conducted their study by observing blood vessel formation in zebrafish embryos. During this process, slow-moving cells are led by a single fast-moving cell. When the lead cell underwent mitosis, it did not become spherical, resulting in two different cells: one slow-moving and one fast-moving to replace the parent cell. Previously, asymmetric cell division was primarily associated with specialized cells known as stem cells.
Holly Lovegrove, co-lead author and a lecturer in cardiovascular sciences at The University of Manchester, explained, “Using transparent one-day-old zebrafish embryos allows us to study a dynamic process like cell division inside a living organism. We are therefore able to make movies of this fundamental cell behavior and in doing so reveal exciting new aspects of how tissues grow.”
The researchers also observed that the shape of the parent cell influences whether its division will be symmetrical or asymmetrical. Shorter and wider cells tended to become spherical and split into two similar daughter cells, while longer and thinner cells did not “round up,” resulting in asymmetrical division.
To explore this further, Herbert, Lovegrove, and their team manipulated the size of human parent cells through micropatterning. Georgia Hulmes, co-first author and a postdoctoral research associate at The University of Manchester’s School of Biological Sciences, described micropatterning as a technique that allows researchers to create specifically shaped microscopic patches of proteins for cells to adhere to, thereby controlling the shape of the cells and examining how these shapes affect cell division.
Herbert noted, “Our research suggests that the shape of the cell before it divides can fundamentally direct whether a cell rounds, and importantly, if its daughters are symmetric or asymmetric both in size and function.”
This discovery could enable scientists to generate cells with different functions by controlling parent cell shapes. More broadly, it suggests that asymmetric divisions are crucial in forming various tissues and organs. The study also has significant implications for diseases such as cancer, where asymmetric division may lead to different cell behaviors potentially linked to cancer progression.
In light of these findings, updates to educational materials may become necessary, impacting students, parents, and school administrators who might need to revise current textbooks.
