Research details previously unknown biological process—cell patterning

Experimental biologists from the Martin Lab at the University of Lausanne headed by faculty member Sophie Martin are experimenting with light to activate mechanisms within genetically modified fission yeast cells. This is one of the research works carried out by them.

Researchers from the university were carrying out similar experiments when they observed that a specific protein, upon introduction into the cell, gets displaced from the cell growth region. The researchers contacted Dimitrios Vavylonis, leading the Vavylonis Group in the Department of Physics at Lehigh University, to find the reason.

We proceeded to make a computational simulation that coupled cell membrane ‘growth’ to protein motion as well as model a few other hypotheses that we considered after discussions with them.”

Dimitrios Vavylonis, Department of Physics, Lehigh University

This interdisciplinary association brought together modeling and experiments to detail an earlier-unknown biological process. The researchers identified and characterized a novel process that a simple yeast cell employs to obtain its shape. The researchers elaborate the findings in a paper called “Cell patterning by secretion-induced plasma membrane flows” published in the journal Science Advances.

According to Vavylonis, during cell growth or movement, cells add a new membrane to the growth regions and this process of membrane delivery is named exocytosis. Cells need to deliver this membrane to a certain location to sustain a sense of direction―known as “polarization”—or to grow in a coordinated manner.

We demonstrated that these processes are coupled: local excess of exocytosis causes some of the proteins attached to the membrane to move (‘flow’) away from the growth region. These proteins that move away mark the non-growing cell region, thus establishing a self-sustaining pattern, which gives rise to the tubular shape of these yeast cells.”

Dimitrios Vavylonis, Department of Physics, Lehigh University

The process for cell patterning—the mechanism by which cells obtain spatial nonuniformities on their surfaces—has been pinpointed for the first time.

The Vavylonis group’s simulations, directed by Postdoctoral Associate David Rutkowski, led to experimental tests, which the Martin group later carried out. Vavylonis and Rutkowski examined the observation of the experiments to validate that the distribution of proteins they observed in their simulations corresponded to the data gathered from the experiments on live cells.

The researchers state that the study can be of specific interest to scientists analyzing mechanisms related to membrane traffic and cell growth like neurobiologists and those investigating cancer cell mechanisms.

Our work shows that patterns in biological systems are generally not static. Patterns establish themselves through physical processes involving continuous flow and turnover.”

David Rutkowski, Postdoctoral Associate, Lehigh University

Vavylonis further remarked, “We were able to provide support for the model of patterning by membrane-flow. In the end, the Martin group was able to use this knowledge to engineer cells whose shape can be controlled by light.”