Using the world’s best tweezers, a team of researchers from the University of Copenhagen has shed new light on a fundamental mechanism in all living cells that helps them detect their surroundings and even invade tissue. . Their discovery could have implications for research into cancer, neurological disorders and more.
Using tentacles like an octopus, a cell pushes toward its target, a bacterium, as a predator tracks down its prey. This scene can be played in a nature program. Instead the chase is being observed at the nano-scale through a microscope at the Niels Bohr Institute at the University of Copenhagen. Microscope recordings show that a human immune cell chases down a bacterium and then eats it.
With their new study, a team of Danish researchers has added to the world’s understanding of how cells use octopus-like tentacles called filopodia to move around in our bodies. This discovery about the way cells move was never addressed. The study is being published today in the renowned journal Nature Communications.
While the cell does not have eyes or a sense of smell, its surface is equipped with ultra-slim filopodia that resemble entangled octopus tentacles. These filopodia help a cell move towards a bacterium, and at the same time, act as sensory sensers that recognize the bacterium as prey.”
Associate Professor Paul Martin Bendix, Head of the Laboratory for Experimental Biophysics, Niels Bohr Institute
The discovery is not that filopodia function as sensory devices – which was already well established – but rather how they can move around and behave mechanically, which helps a cell move. such as when a cancer cell invades new tissue.
“Obviously, our results are of interest to cancer researchers. Cancer cells are known for their highly aggressive nature. And, it is reasonable to believe that they are dependent on the efficacy of their filopodia, in particular, of their surroundings. It is conceivable, therefore, that finding ways to inhibit the filopodia of cancer cells, could prevent the development of cancer,” explains Associate Professor Paul Martin Bendix.
For this reason, researchers from the Danish Cancer Society Research Center are part of the team behind the discovery. Among other things, cancer researchers are interested in whether turning off the production of certain proteins can disrupt transport mechanisms that are important for cancer cells’ filopodia.
Sail engine and cutting torch
According to Paul Martin Bendix, the mechanical function of filopodia can be compared to that of a rubber band. Without turning, the rubber band has no power. But if you bend it, it shrinks. This combination of twisting and contraction helps a cell to move upright and makes filopodia very flexible.
“They are able to bend -; bend, if you will -; in a way that allows them to explore the entire space around the cell, and they can even penetrate tissues in their environment,” said lead author, Natasha Legions says.
The mechanism discovered by Danish researchers is found in all living cells. In addition to cancer cells, it is also relevant to study the importance of filopodia in other cell types, such as embryonic stem cells and brain cells, which are highly dependent on filopodia for their development.
Studying Cells With the World’s Best Tweezers
The project involved interdisciplinary collaboration at the Niels Bohr Institute, where Associate Professor Amin Dostmohamedi, who leads a research group that simulates biologically active materials, contributed to the modeling of filopodia behavior.
Paul Martin Bendix explains, “It is very interesting that Amin DostMohamed can simulate mechanical movements observed through a microscope, which are completely independent of chemical and biological details.”
The main reason the team was able to first describe the mechanical behavior of filopodia is because NBI has unique equipment for this type of experiment, as well as skilled researchers with tremendous experience working with optical tweezers. When an object is exceptionally small, it becomes impossible to hold it mechanically. However, it can be conducted and moved using a laser beam with a wavelength carefully calibrated for the object being studied. This is called optical tweezers.
“At NBI, we have some of the world’s best optical tweezers for biomechanical studies. The experiments require the use of multiple optical tweezers and the simultaneous deployment of ultra-fine microscopy,” explains Paul Martin Bendix.
The study was led by NBI Technical Scientist Yunus Baruji, along with Paul Martin Bendix and Assistant Professor Natasha Legance. Article on cell filopodia is published today nature communication,
University of Copenhagen – Faculty of Science
Legionné, N., and others. (2022) Filopodia spin and coil by actively generating twists in their actin shafts. nature communication, doi.org/10.1038/s41467-022-28961-x.