• New sleep molecule discovered: 'It shows

    From ScienceDaily@1:317/3 to All on Fri Apr 29 22:30:48 2022
    New sleep molecule discovered: 'It shows just how complex the machinery
    of sleep is'

    Date:
    April 29, 2022
    Source:
    University of Copenhagen - The Faculty of Health and Medical
    Sciences
    Summary:
    Researchers presents a new study demonstrating that a small
    molecule in brain cells affects the level of hypocretin, which
    is responsible for making us feel awake during the day and tired
    at night. People with a genetic variation of this molecule have
    a higher risk of suffering from daytime sleepiness.



    FULL STORY ========================================================================== Researchers from the University of Copenhagen and Aalborg University
    presents a new study demonstrating that a small molecule in brain cells
    affects the level of hypocretin, which is responsible for making us feel
    awake during the day and tired at night. People with a genetic variation
    of this molecule have a higher risk of suffering from daytime sleepiness.


    ==========================================================================
    When brain scientist Birgitte Kornum from the Department of Neuroscience recently arrived in Rome for one of the largest sleep conferences in
    the world, she was completely taken aback. There were pharmaceutical
    companies everywhere -- with stands, information material and campaigns.

    They all wanted to treat daytime sleepiness or to turn off the brain
    at night.

    And a lot of them focussed on hypocretin, which is a protein found in
    brain cells and which has recently attracted a lot of attention within
    sleep research.

    This is because hypocretin is suspected to play a role in both insomnia,
    which is a decreased ability to fall asleep at night, and in narcolepsy,
    which is a decreased ability to stay awake during the day. People
    suffering from insomnia may have too much hypocretin in the brain, while
    people suffering from narcolepsy have too little. Researchers also suspect hypocretin to play a role in depression, ADHD and other mental disorders.

    A lot is already known about the hypocretin system in the brain. There
    is even a new drug for insomnia countering the effect of hypocretin,
    latest introduced in Canada in 2018. According to Birgitte Kornum, though,
    the problem is that we know very little about how hypocretin is regulated inside the cells.

    Therefore, Associate Professor Birgitte Kornum and her colleagues set
    out to shed light on the issue in a new study, which has recently been published in the reputed journalPNAS. The study combines tests on mice, zebrafish and human cells, and the researchers cooperated with their
    neighbours at the University of Copenhagen's Department of Cellular and Molecular Medicine, among others.



    ========================================================================== MicroRNA associated with sleep regulation The team of researchers have
    spent several years studying one of the cellular mechanisms that affect hypocretin levels. Here they have focussed on a small molecule called microRNA-137 (miR-137).

    "We discovered that miR-137 helps regulate hypocretin. To experience
    normal sleep, you need to have the right amount of hypocretin in the
    brain at the right time, and miR-137 helps with that. Though MiR-137 is
    also found in other parts of the body, it is especially pronounced in the brain," Birgitte Kornum says about the new study, which she has headed
    together with Assistant Professor Anja Holm from Aalborg University.

    MicroRNA regulates various cellular processes, including hypocretin
    levels.

    Therefore, there is considerable research interest in microRNAs, as they
    could be targeted in order to regulate such processes.

    Previously, the scientists knew very little about the role played
    by miR-137 in the brain, but now Birgitte Kornum's research team has demonstrated that it is associated with hypocretin regulation and thus
    with sleep.



    ========================================================================== "This is the first time a microRNA is associated with sleep
    regulation. Drawing on the UK Biobank, we discovered some genetic
    mutations in miR-137 which cause daytime sleepiness. The study
    demonstrates this connection in both mice and zebrafish, and we are
    able to prove the connection with hypocretin. Our discovery shows just
    how complex the machinery of sleep is. Imagine inheriting a variant of
    miR-137 that puts you at higher risk of feeling sleepy during the day,"
    says Birgitte Kornum.

    Hypocretin affects sleep stages Hypocretin, which has caught the
    attention of the pharmaceutical companies, also affects the order of
    the sleep stages.

    Our sleep is usually divided into four stages. The stages follow a
    specific order, and this order is vital to the quality of our sleep.

    "Narcolepsy patients suffering from low levels of hypocretin experience
    muddled sleep stages. We know this from mice tests demonstrating that hypocretin affects the order of these stages," explains Anja Holm from
    Aalborg University, who is first author of the study and who did the
    tests together with Birgitte Kornum.

    Existing research suggests that to solve the problem we need to gain
    more knowledge of hypocretin regulation. And here the Danish researchers
    point to a different, but equally important piece of the puzzle, namely
    the immune system.

    "Most people know that when you are ill you often feel tired. And when you
    have a fever and the immune system is hard at work, you often suffer from
    poor sleep. So we know that something happens to the hypocretin level
    when the body is trying to fight off a virus infection, for example,
    and we are trying to understand this process," says Birgitte Kornum.

    "In the study, we show that one of the immune system's transmitter
    substances, IL-13, has a special effect on hypocretin. We can tell
    that when we add IL-13, it affects miR-137 and thus also the level of hypocretin in the body. We still do not know why, though, but we are
    currently doing tests that may be able to give us an answer."

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


    ========================================================================== Journal Reference:
    1. Anja Holm, Marie-Laure Possovre, Mojtaba Bandarabadi, Kristine F.

    Moseholm, Jessica L. Justinussen, Ivan Bozic, Rene'
    Lemcke, Yoan Arribat, Francesca Amati, Asli Silahtaroglu,
    Maxime Juventin, Antoine Adamantidis, Mehdi Tafti, Birgitte
    R. Kornum. The evolutionarily conserved miRNA-137 targets the
    neuropeptide hypocretin/orexin and modulates the wake to sleep
    ratio. Proceedings of the National Academy of Sciences, 2022; 119
    (17) DOI: 10.1073/pnas.2112225119 ==========================================================================

    Link to news story: https://www.sciencedaily.com/releases/2022/04/220429144940.htm

    --- up 8 weeks, 4 days, 10 hours, 51 minutes
    * Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (1:317/3)