• With help from the best tweezers in the

    From ScienceDaily@1:317/3 to All on Mon Mar 28 22:30:40 2022
    With help from the best tweezers in the world a team of researchers from
    the University of Copenhagen has shed new light on a fundamental mechanism in all living cells that helps them explore their surroundings and even invade tissue

    Date:
    March 28, 2022
    Source:
    University of Copenhagen - Faculty of Science
    Summary:
    With help from the best tweezers in the world a team of researchers
    has shed new light on a fundamental mechanism in all living
    cells that helps them explore their surroundings and even invade
    tissue. Their discovery could have implications for research into
    cancer, neurological disorders and much else.



    FULL STORY ==========================================================================
    With help from the best tweezers in the world a team of researchers
    from the University of Copenhagen has shed new light on a fundamental
    mechanism in all living cells that helps them explore their surroundings
    and even invade tissue.

    Their discovery could have implications for research into cancer,
    neurological disorders and much else.


    ========================================================================== Using octopus-like tentacles, a cell pushes toward its target, a
    bacterium, like a predator tracking down its prey. The scene could be
    playing out in a nature programme. Instead the pursuit is being observed
    at the nano-scale through a microscope at the University of Copenhagen's
    Niels Bohr Institute.

    The microscope recording shows a human immune cell pursuing and then
    devouring a bacterium.

    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 how cells
    move had never been addressed. The study is being published today in
    the journal, Nature Communications.

    "While the cell doesn't 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 feelers that identify the bacterium as
    a prey," explains Associate Professor Poul Martin Bendix, head of the laboratory for experimental biophysics at the Niels Bohr Institute.

    The discovery is not that filopodia act as sensory devices -- which
    was already well established -- but rather about how they can rotate
    and behave mechanically, which helps a cell move, as when a cancer cell
    invades new tissue.

    "Obviously, our results are of interest to cancer researchers. Cancer
    cells are noted for their being highly invasive. And, it is reasonable
    to believe that they are especially dependent on the efficacy of their filopodia, in terms of examining their surroundings and facilitating
    their spread. So, it's conceivable that by finding ways of inhibiting
    the filopodia of cancer cells, cancer growth can be stalled," explains Associate Professor Poul Martin Bendix.



    ==========================================================================
    For this reason, researchers from the Danish Cancer Society Research
    Center are a part of the team behind the discovery. Among other things,
    the cancer researchers are interested in whether switching off the
    production of certain proteins can inhibit the transport mechanisms
    which are important for the filopodia of cancer cells.

    The cell's engine and cutting torch According to Poul Martin Bendix,
    the mechanical function of filopodia can be compared to a rubber
    band. Untwisted, a rubber band has no power. But if you twist it, it
    contracts. This combination of twisting and contraction helps a cell
    move directionally and makes the filopodia very flexible.

    "They're able to bend -- twist, 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," says lead author, Natascha Leijnse.

    The mechanism discovered by the Danish researchers appears to be found
    in all living cells. Besides cancer cells, it is also relevant to study
    the importance of filopodia in other types of cells, such as embryonic
    stem cells and brain cells, which are highly dependent on filopodia for
    their development.



    ========================================================================== Studying cells with the best tweezers in the world The project involved interdisciplinary collaboration at the Niels Bohr Institute, where
    Associate Professor Amin Doostmohammadi, who heads a research group that simulates biologically active materials, contributed with the modelling
    of filopodia behaviour.

    "It is very interesting that Amin Doostmohammadi could simulate the
    mechanical movements we witnessed through the microscope, completely independent of chemical and biological details," explains Poul Martin
    Bendix.

    The main reason that the team succeeded in being the first to
    describe the mechanical behaviour of filopodia is that 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 extraordinarily small, holding onto it mechanically becomes impossible. However, it can be held and moved using a laser beam with
    a wavelength carefully calibrated to the object being studied. This is
    called an optical tweezers.

    "At NBI, we have some of the world's best optical tweezers for
    biomechanical studies. The experiments require the use of several optical tweezers and the simultaneous deployment of ultra-fine microscopy,"
    explains Poul Martin Bendix.

    Leading the study alongside Poul Martin Bendix and Assistant Professor
    Natascha Leijnse was NBI Technical Scientist Younes Barooji. The article
    on cell filopodia is published today in Nature Communications.


    ========================================================================== Story Source: Materials provided by University_of_Copenhagen_-_Faculty_of_Science. Note: Content may be
    edited for style and length.


    ========================================================================== Journal Reference:
    1. Natascha Leijnse, Younes Farhangi Barooji, Mohammad Reza Arastoo,
    Stine
    Lauritzen So/nder, Bram Verhagen, Lena Wullkopf, Janine Terra
    Erler, Szabolcs Semsey, Jesper Nylandsted, Lene Broeng Oddershede,
    Amin Doostmohammadi, Poul Martin Bendix. Filopodia rotate and
    coil by actively generating twist in their actin shaft. Nature
    Communications, 2022; 13 (1) DOI: 10.1038/s41467-022-28961-x ==========================================================================

    Link to news story: https://www.sciencedaily.com/releases/2022/03/220328090014.htm

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