• Membraneless organelles: From liquid to

    From ScienceDaily@1:317/3 to All on Thu Mar 24 22:30:44 2022
    Membraneless organelles: From liquid to solid to drive development


    Date:
    March 24, 2022
    Source:
    European Molecular Biology Laboratory
    Summary:
    Researchers show that transition from liquid to solid is important
    for the function of membraneless organelles.



    FULL STORY ==========================================================================
    The term 'phase transition' might initially conjure up images of ice
    melting or water vapour condensing on a cold glass. In biology, phase transition plays a role in processes such as lipid bilayer formation
    or the spontaneous de-mixing of protein droplets. In a recent paper
    published in Cell, the Ephrussi and Mahamid groups at EMBL Heidelberg
    have now shown how phase transitions in protein-RNA droplets can influence their biological function.


    ==========================================================================
    In order to regulate the many cellular functions within an organism, biochemical processes within individual cells must be precisely regulated
    in time and space. While organelles like the nucleus or the endoplasmic reticulum are enclosed by membranes and thereby physically separate
    certain reactions and processes from others, the cellular space also
    contains a different class of organelles without membranes, called
    condensates. Like their membrane-bound counterparts, condensates control specific functions within a cell.

    In their latest study, the EMBL scientists focused on one specific
    mRNA, oskar, and its role in embryo development in the model organism Drosophila melanogaster (fruit fly). In the developing fruit fly egg,
    oskar mRNA must localise to a specific position within the cell to lay
    the foundation for the development of the future embryo. oskar mRNA is
    found in ribonucleoprotein (RNP) granules that contain proteins bound to
    the RNA. These are an example of membraneless condensates. What the EMBL researchers were now able to show is that these granules have solid-like properties in the developing fruit fly egg.

    "Condensates are typically thought of as liquids. But we found that
    a solid state of oskar RNP granules is crucial for localisation and
    function of oskar mRNA," explained Mainak Bose, postdoc in the Ephrussi
    and Mahamid groups, and first author of the study. "When we genetically engineered the granules in Drosophila oocytes to be liquid-like,
    it resulted in a multitude of defects in the developing embryos."
    These findings demonstrate the importance of the physical properties of condensates for their physiological functions, something that was until
    now believed to be governed by their biochemical properties alone. "Our
    work highlights how interactions and properties at the molecular level
    govern the biophysical properties and functions of condensates on the
    cellular and even organismal scale," concluded Bose.


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


    ========================================================================== Journal Reference:
    1. Mainak Bose, Marko Lampe, Julia Mahamid, Anne
    Ephrussi. Liquid-to-solid
    phase transition of oskar ribonucleoprotein granules is essential
    for their function in Drosophila embryonic development. Cell,
    2022; DOI: 10.1016/j.cell.2022.02.022 ==========================================================================

    Link to news story: https://www.sciencedaily.com/releases/2022/03/220324104552.htm

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